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User's Guide ©2001 Robert McCaa, Department of History and University of Minnesota Population Center | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Basics | Populate is designed to be used with minimal reference to this guide. However, to better understand both the operation of the program as well as the features and flaws of the inverse projection method some familiarity with the guide is useful. The guide is organized in seven sections, as follows: 1. Introduction: Why Populate, Hotkeys, Help, Common Commands, Speed Populating, and a note on method. 2. Two experiments or examples: 3. Composing Models: If ... . 4. Screen display 5. Data and data files 6. Miscellaneous (enhancements v. 2-2.9, formulas) 7. Glossary: definition of terms, from Active to Zoom | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Windows compatibility |
Compatibility with Windows programs, such as EXCEL, is straight-forward.
Demanding users will appreciate having a carefully calibrated inverse projection program. Forgiving users will readily adjust to controls located at the bottom of the screen instead of the top, to the fact that commands are capitalized instead of underscored, or that they are activated by a single key stroke instead of having to simultaneously depress the Populate is a truly "event-driven" program. It is designed to encourage the user to quickly, and on-the-fly, test alternative scenarios ("What-IF?"), edit data, and invoke commands in almost any order. Multiple scenarios can be projected in a single session and a wide range of demographic statistics compared quickly and easily by tapping a few keys. Results may be viewed as graphics or tables by means of a single key-stroke. Populate was written in 1986 for a DOS operating system, long before Windows existed. Populate's computational formulas have been carefully calibrated. Upgrading the program to Windows is not a simply a matter of a face-lift, but instead involves a not inconsiderable investment of programming time. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Menus | Three menus--Main, Options, If--provide the tools to run the program. Each menu contains 8-10 commands (actions). Tapping the capitalized letter of a prompt (also underscored here) activates the command. Most commands are common to the core menus:
File Graphics Help If Learn Models Note Options Quit Record Statistics Tables View Wipe Zoom Only three are unique to a single menu. They begin with the letters C, A, or P (italicized below). The core menus and their commands are as follows:
Populate Graphics Tables IF Help Learn Note Options View Wipe Quit Options Graphics Tables File Record Configure Axis Models Statistics View Zoom If Age Constant Lifetable Variable Quit Help | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Hotkeys | To activate a command, tap its hotkey, the first, capitalized letter of the command word. If the command is an action (example: Populate), tapping its hotkey--either lower or upper case--executes the action. Thus, tapping "P" (Populate) at the main menu projects the currently specified model.
If the command is a condition, or option, the feature is toggled on or off. "!" indicates that a condition is on; "." that it is off. Tap the corresponding hotkey to activate or toggle the command. Upper and lower case hotkeys are indistinguishable to the program, expect on the variables menu and even then only when the number of variables is 32 or greater. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Help | When in doubt, simply tap H for help. A context-specific description of each menu and its commands is available by tapping H. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Help Menu | Tap H again to obtain a description of each help command (Figure 3). Examine any of the help commands listed by tapping the first letter of a help word. To return to the main menu, tap the <Esc> key. To skip over the current help screen tap <Tab>. To view a different help screen tap the first letter of a help key word (Figure 3). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 3. |
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| 9 Universal keys | The following commands may be activated at any menu: <Esc> - escape directly to the main menu. <spacebar> - space one step toward the main menu. H - display help information for the current command line. N - type a note, comments or reactions to findings or whatever at almost any moment (except when editing or calculating). Notes are filed with the statistical results from each model. Q - Quit; stop the session. W - Wipe the screen, when it becomes cluttered. <PrtSc>} - paste text from any screen to the Windows clipboard; tap the <PrtSc> key. <!> - begin a lesson (and record keystrokes in a .lrn file), tap !. Tapping ! again, stops the recorder to end the lesson. <\> - pause the lesson (or recorder), tap \ again to restart. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 15 Common commands and hotkeys | The following commands, and their corresponding hotkeys, are common to core menus: File - write statistics to the results file (toggle on or off). Graphics - turn graphics on or off (not available on text systems). Help - explain the current screen. If - define a scenario for the next projection. Learn - select a tutorial from the menu of available lessons. Models - list the conditions which produced each projection (when there is more than one model). Note - write a note to the results file. Options - change screen display settings (axis, colors). Quit - quit Populate; return to the operating system. Record - when on, save each keystroke and comment to the xxx.lrn file for use as a tutorial in a subsequent session; R or <!> also toggles the recorder on/off; <\> pauses; tap <\> again to restart the recorder. Statistics - select demographic statistics to be displayed. Tables - turn tables display on or off. View - choose a model to display statistics on the screen for a selected model. Wipe - wipe the screen of all graphics and text. Zoom - display statistics for selected years at specified intervals. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Menu-specific keys | There are three keys (cap) on each menu which invoke commands specific to that menu. For example, a projection can be started only by tapping P (to Populate) when the main menu is displayed. Main (Populate) menu: Populate - project the current model Options menu: Axis - change the vertical axis of any statistic Configure - reconfigure adapter, background and/or graphics colors for statistics If menu (these commands are invoked solely from this menu): Age - change age structures for a specific period Constant - change initial population size or birth, death or migration rates by a constant factor for an entire projection Lifetable - select a mortality or age structure from the set of lifetables Variable - change the values for a selected variable at a specific moment | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Unassigned keys=continue | When an unassigned key or <spacebar> is tapped, the cursor moves one step toward the main menu. The phrase "else continue" means strike <spacebar> or an unassigned key to move toward the main menu. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <Enter> key | When a prompt requests that a response be entered, key some data then tap <enter>. In any instance where data are requested, the program will not continue, until <Enter> or <return> is tapped. Tapping <enter> with no data causes default values to be inserted. When in doubt, tap enter. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Colors | For each projection, Populate computes the following statistics at five year intervals:
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| Method: Inverse projection | Populate is based on Lee's inverse projection method, but developed independently of his program, Inverse. Populate will not exactly replicate results from Inverse. Estimates from both programs are remarkably similar. Moreover, Populate produces estimates that uncannily parallel results from:
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| Flexibility | Populate manages the demographic history of England for the period 1541 to 1871 with a very great number of models (unlimited when results are stored exclusively in computer memory) each made up of a complex variety of assumptions. Moreover the results of any of a dozen projections can be displayed instantly on the computer screen.
Tables may be transferred to paper with a few menu-prompted key strokes. Presentation quality graphics are easily prepared from a results file with standard microcomputer software (Stata, Spsspc+, EXCEL, etc.) or may be copied from the screen and pasted directly into any Windows document that recognizes the clipboard. Model selection and testing capabilities are superior, a matter of a few key-strokes and comparing graphs or tables on the fly. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Calibration and precision. | Equally important, Populate is not only precise but also fairly calibrated. While Populate's computations are accurate to fourteen digits, the results are displayed to a maximum of only six to limit spurious inferences. The program has proven its robustness against one of the longest, most respected series of historical vital events available, that for Norway stretching from 1736 to 1970. Populate was also calibrated against simulated projections--where there is no room for error. In a double-blind experiment using fourteen sets of data covering the range of historical demographic experience, the program's goodness-of-fit procedure quickly and easily tracked the quarry, yielding life expectancies, population pyramids, and fertility ratios nearly identical to the targets. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Silly results | Careful study of Lee's method is necessary to appreciate fully its strengths and weaknesses. With Inverse or Populate, silly assumptions produce silly results. Populate helps the cautious projectionist distinguish the silly from the sound. Thus, this program accommodates not only ZPG (zero population growth) but also ZB or ZD (zero births or zero deaths)! Faulty data or suppositions may be readily exposed by a single If. Sound data and reasonable assumptions should lead to insights on the basic demography of the past and perhaps the future. Try Populate with data selected from USA.pop or LA.pop to peer into the demographic future of the Americas. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 2. Examples: Two Experiments | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| The following experiments display the features of the program and the power of the inverse method, but they also reveal the contours of the English demographic revolution and the cornerstone of the science of demography. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| England, 1541-1871 | The first experiment examines the English demographic revolution (1740-1840) using the birth and death series developed by the Cambridge Group for the History of Population and Social Structure. The authors, E. A. Wrigley and Roger Schofield, convincingly argue that the population of England barely doubled from 1541 to 1741. In the following century, a major demographic shift occurred, causing England's population to triple and continue to grow rapidly for several decades. The debate over the causes of the modern rise of the English population has fascinated historians, medical doctors, and others for some time. Populate allows you to consider the various hypotheses and muse over the question yourself. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 4. |
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| England.pop | From Windows Explorer or the desktop (see installation), click "populate.com" to start Populate. At the first menu, tap E to analyze the English data. If the program indicates that the file England.pop is not found, tap Q to Quit, then use Windows explorer to find the file and move it into the Populate folder. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| When calculations begin, a title and specifications of the current model are displayed at the top of the screen, and the year and projected population at the bottom. Populating. . .1541 2724 In a second or so, three hundred years of English population history, marked at quarter century intervals, will appear, displaying the following statistics: total population, crude birth and death rates, net reproduction ratio, and life expectancy at birth (Figure 4). Once the statistical results are displayed on the screen, open the Populate menu by tapping any key. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| The English demographic revolution, reconsidered. | The debate centers on the role of changing vital rates. Was this early modern population explosion, which lasted from 1761 to 1871, due to a decline in death rates or rising birth rates? To test the various explanations, alternative birth and death series can be brought into play (tap Learn A to do the experiment as a tutorial). The baseline, Model a, must be revised to take into account estimated migration rates, instead of counts (a close approximation of a, Model b). Activating the rate variable, forces the level of migration to remain the same throughout the experiment. The experiment proceeds by first varying death, then birth, rates to observe the effect on total population. Thus, three additional models are required: c, the "no revolution" model with constant mortality and fertility; d, mortality, with death rates following their observed course but fertility held constant at its early modern norm; and e, fertility follows its historical course and mortality is held constant. For the moment the interplay between rates will be ignored. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Experiment 1. |
The English Demographic Revolution: Driven by Mortality or Fertility?
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| Composing models. | To compose model b, tap If Variables and examine the menu of variables available for the analysis. Toggle the migration rate variable, "Migrlee" on (F on the variable menu), as well as the observed birth and death rate variables (KM). Escape to the main menu (tap <Esc>), and project model b (tap P, name the model " Base"). When computations are complete, compare model a and b to observe their strong similarities. The small differences are due to two changes: first, the use of midpoint birth and death rates generated by Populate in a previous session and then re-cycled here, and second, switching from Wrigley and Schofield's estimated net migration counts to Lee's hypothesized long swings in out-migration (.0015 per annum 1539-1693, .00085 for 1694-1798, from .0002 to .0014 for 1799 to 1863, then to .001 in 1871). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Models c, d, e | Continue the experiment by constructing models c (If Variable Ibcnst Jdcnst <esc> Populate Norev), d (If Variable Mdobsrvd <esc> Populate Morta), and e (If Variable Jdcnst Kbobsrvd <esc> Populate Ferti). Now View List models ABCDE <spacebar> and select the statistic total Population (Figure 5). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 5. |
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| England's late 18th century baby boom and early nineteenth century falling death rates. | What would the English population have looked like, if vital rates had continued along the path of the two preceding centuries? Model c shows that there would have been no revolution, that in 1871 the population of England would have stood at less than 10 million, instead of almost 22. Models d and e suggest that both changing death and birth rates accounted for the unprecedented surge in population, but that the fertility effect (7 million) was more than twice as great as that of mortality (3 million). The unaccounted 2 million might be attributed to mortality decline (rising fertility increases mortality where infant deaths constitute a substantial fraction of total deaths) or interaction between both factors. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net reproduction ratio | The most telling evidence is given by the net reproduction ratio, which measures actual reproductive performance by taking both mortality and fertility into account (Figure 6; to view on the screen select: Graphics or Tables, Statistics toggle off all variables except Nrr, then View BCDE). From 1766 to 1816, the fertility model closely tracks the growth rate of the baseline model. During the first half century of England's population revolution, the generational growth rate rose steadily. For the next half century (1816-1866), reproduction remained high, but the conditions for growth shifted from rising birth rates to falling death rates (model b and d). This experiment supports Wrigley and Schofield's conclusion that the rise in fertility was the most significant factor and that it preceded mortality decline by at least a quarter century. For the half century from 1766 to 1816, fertility change accounted for 90% of the demographic revolution. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 6. | Net Generational Growth Rates (Nrr) Estimated by 4 Models B - Baseline, C - No revolution, D - Mortality, E - Fertility @graph here | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| It would be misleading to conclude the story here, without examining the series in detail (five year intervals instead of twenty-five) or taking into account exogenous variables such as real wages, passion between the sexes, urbanization, and the like. Populate offers a solution to the former (from the main menu, tap Zoom 1761 <enter> 1841 <enter> 5 <enter> to focus on the critical period and set the interval between observations at five years). For the latter, information outside this dataset is required. Wrigley and Schofield, in the concluding chapter of The Population History of England, 1541-1871: A Reconstruction, carefully delineate the structural shifts which occurred in English demographic behavior. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Experiment 2. Vital rates, not initial states: Inverse and Back Projection Compared
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| Inverse projection | The second experiment examines the methodological underpinnings of inverse projection. Lee called his approach "inverse", because it inverts conventional projection procedures. Instead of specifying age specific conditions for future periods and deriving population size and crude rates, Lee's projection method inverts the process to elicit age specific measures from crude data. Similarly, Lee also turns the well known back projection method used by Wrigley and Schofield on its head. Rather than starting with the "best" data that one has and "projecting" back into the remote past as Wrigley and Schofield did in their ingenious, path breaking study of England, he inverted their procedure, beginning in the distant past and projecting forward, using more or less arbitrary assumptions about initial age and mortality patterns. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Why age structure is important. | What difference does age structure make? None at all, when the issue is total population size or crude rates. But advances in the debate over the demographic determinants of the modern rise of English population require more refined measures of mortality (life expectancy) and fertility (gross reproduction ratio), which in turn depend upon age structure. In the absence of a national census, two methods are available for estimating age structure and age dependent demographic measures from simple counts of births and deaths: back projection and inverse projection. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Back projection | Wrigley and Schofield sought to exploit the earliest known, best age structure of the English population, that from the census of 1871, and work their way back as far as baptismal and burial registers permit, to 1541. Thus every hump and bump of the 1871 population pyramid of England became their starting point. Counts for ages at which reporting is notoriously inaccurate--75-79, 80-84, even 85-89--are critical for their method. Put simply and without consideration of the many cunning uses of computers and demographic theory, they projected the English population backward, by subtracting births from the base of the pyramid, adding deaths to the various age groups along its slope and creating a new peak. This essentially shoved the pyramid down a layer, that is, back five years. Back projections were repeated 65 times at five year intervals to arrive at an estimate of the age pyramid for 1541. Moreover many iterations, or sets of projections, were made to extract the single set which best satisfied complex statistical and demographic tests. By means of much energy and imagination, the Cambridge Group constructed a landmark series of demographic statistics at five year intervals, including estimates of life expectancy, fertility, and even population age structure stretching over a period of more than three centuries. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inverse projection | Lee questions the theoretical underpinnings of back projection. He argues that the concern with initial states, the age structure of England in 1871, is misplaced, that vital rates, birth and death series, are the critical factors. The foundations of inverse projection lie in the 1920s with the work of H. T. J. Norton on the weak ergodicity theorem and its rediscovery by Alvaro Lopez in 1961. It rests on what Kenneth Wachter has called "the cornerstone of formal demography", the notion that, in the long run, vital rates, not initial states, determine what a population will look like. Lee noted that populations rapidly "forget" their age structure, even following substantial mortality or fertility fluctuations (Lee, 1985:234). Two conclusions immediately follow. First, Wrigley and Schofield's concern with empirically derived starting assumptions may not be as critical as they assumed. Secondly, the effects of more or less arbitrary assumptions necessary to initiate an inverse projection vanish rather quickly (say, in a half century) and with hardly a trace. Populate makes it possible to quickly and easily conduct an experiment to judge the merits of Lee's argument. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inverse vs. back projection | Figure 7 compares back projection estimates of life expectancy of England with the results from Model A. The figure shows that inverse projection produces estimates that are almost identical to back projection, when the hypothesized initial states are more or less reasonable. What is reasonable? | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 7. | Life Expectancy from Back and Inverse Projections, England 1541-1871 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| A test of the weak ergodicity theorem. | Consider what happens to estimates of mortality and fertility when different, even highly unlikely, assumptions are made. The baseline is Figure 4 (above, to view on screen, tap View A), that is, the age structure and mortality levels for England from 1541 to 1871, using the Cambridge Group's data and assumptions. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Model f, an approximation. | Model f, with mortality and age structure characteristic of a "West" population with life expectancy at birth of 37.5 years and growth rate of .8% per annum, attempts to approximate, without duplicating, the baseline from the set of 200 life tables available in Populate. Models g and i are designed to answer the question: What happens if even absurd age and mortality suppositions are made? Model g uses life chances more characteristic of the twentieth century than the sixteenth (57.5 years; the life expectancy in Britain at the beginning of the twentieth century stood at 48 years). Model i hypothesizes twentieth century fertility characteristic of, say, Latin America in the 1940s. Each model can be specified and projected with a half dozen mnemonically prompted keystrokes. The entire experiment can be conducted by tapping L to activate Learn, then selecting lesson "B", and following instructions as they appear above the command line at the bottom of the screen. The following supplements the instructions in lesson b. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Experiment 2. |
Vital Rates versus Initial States
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| Testing Lee's hypothesis. | First, set the conditions for model f. Tap I to turn to the If menu, then L to access Lifetables, W for region West, I to retrieve the 37.5 model life table, then type 8 <enter> to generate the age structure of a "western" population with a life expectancy at birth of 37.5 years and a rate of natural increase of 0.8% per annum. The variables "Lw37" and "A37r8" are activated (signaled by a "!" in the variable menu at the top of the screen). This assigns to the population of England in 1541 the age structure of a moderately growing "western" population and a western age pattern of dying with a life expectancy at birth of 37.5 years. Note that previous age and mortality conditions ("Lxlee" and "Agew+s") automatically become inactive when new conditions are set. Select "Migrate" (tap E) to re-activate Wrigley and Schofield's estimates of net migration. Tap <esc> to regain the main menu, then tap P to Populate. Name the model (e.g., "Close") and compute. The identification of the model at the top of the screen includes "LW37" for survival probabilities from model life table West 37.5, and "AW37r8" for the age structure from the same life table with a growth rate of 8 per thousand. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| When computations for model f finish, instead of pausing to compare it with model a, quickly specify and project model g (If Lifetable West T8<esc> Populate Lodth), and i (If Lifetable West I20<esc> Populate Hibir). | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Results | The results from these models demonstrate the power of Lee's method. First, reset the Zoom feature to focus on the period 1541-1621 (Z1541<enter>1621<enter>5<enter>). To compare say, life expectancy, tap View, List model AFGI<spacebar>, Life expectancy (tap VLAFGI<spacebar>L). The tabular display (Figure 8) shows that by 1601, the largest divergence in life expectancy at birth between model a and the others is less than one year! This is a trivial difference indeed, considering the enormous difficulties in constructing the data on which Wrigley and Schofield's estimates are based. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 8. |
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Selecting GRR to compare the course of fertility according to the four models reveals differences of less than 15% within twenty-five years (less than 5% after a half century). Even differences in estimates of the net reproduction ratio reduce to a matter of a few points within a half century of the start of the inverse projection. Finally, to observe the evolution of a portion of the English population pyramid, select an age group by tapping A <spacebar>, typing a group (e.g., 0, 0-14, 15-49, or whatever), and tapping <enter>. This display and all age-dependent statistics from this experiment support Lee's argument about the robustness of the inverse method. Thus, population projections of the past are greatly simplified. With good data and a long series of fifty or more years, informed, perhaps even arbitrary assumptions generate reasonable results. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| When inverse fails | Wachter sounds a note of caution, noting particular conditions under which ergodicity, and inverse projection, can fail (pp. 286-7). The key is "K", the index of mortality variability, and K2 (the sum of K*K for each period). As long as life expectancy is less than 77.5 (the current limit of readily available model life tables), K squared scores can be used to determine whether the various demographic inputs fit together well. By experimenting with different age patterns of mortality, the single model which fits best (produces the smallest K2) can be identified. Moreover, the If Age procedure (section 3) provides for even more fine-tuning, permitting adjustments to be made for different mortality or fertility patterns and even age structures for any period in the projection. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 9. | The Diminishing Effect of Initial States: Gross Reproduction Ratio under Four Assumptions | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
@graph here | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Graphics views | Populate quickly plots any of its demographic statistics to the screen. Tables View List is available to compare the numerical results from many models, one statistic at a time. To view the big picture, reset zoom to 1541-1641 (<esc>Z<enter> 1641 <enter> <enter>). For a graphical view toggle Graphics on, by tapping G at the main menu, Wipe the screen, select a single age-dependent statistic (e.g.,Statistics Grr; toggle Population, Birth, Death and Life off, and tap <spacebar>), and then View models afgi in rapid succession. (To accomplish a similar effect in text view, tap VLAFGI<spacebar>G, to list the gross reproduction ratios for models a, f, g, and i.) The screen will display a visual image of the very slight importance of the age assumption on fertility estimates and further confirm the power of Lee's inverse method (Figure 9). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| To view changes in age structure, Wipe the screen, return to the statistics menu (<spacebar>S), toggle Grr off and Sumage on, then <spacebar> View A. This displays the cumulative age distribution of England's population over more than three centuries. Note the extraordinary volatility of the age structures of past populations. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| For a graphic demonstration of how quickly vital rates overwhelm initial states tap FGI. (On non-graphics systems, use View List AFGI Age <enter> 0-14 <enter>, for a similar effect.) This is not to say that age structure settings are trivial or unimportant, but that in the long run vital rates are the most powerful determinants, as these figures show. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| When age is important | The importance of changing vital rates on age structures can be appreciated by reviewing results from experiment 1. Wipe the screen and tap BCDE to examine the effects of a European demographic revolution on age structures. C reveals the age structure that would have emerged under constant mortality and fertility rates; D weighs the effects of changing mortality, and E shows what would have happened if fertility alone had changed and mortality stayed constant. Whether these results are viewed as graphs or tables, they allow one to easily discern the comparative effects of mortality and fertility on the English age structure. Note that fertility, not mortality, change had--and as a matter of principle, always has--the most dramatic impact. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Conclusion | These experiments illustrate the power of Lee's inverse method and the range of features available with Populate. Commands, menus, and additional features are explained in sections three and four, and data preparation, in section five. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
3. Composing Models: If. . . | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If | This section examines the "If" command, the starting point for changing any of the conditions or data used in a projection from within the program. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Impulse modeling | The possibility of adjusting births, deaths, migration, etc. for any years without exiting from the program allows for a great deal of flexibility in modeling. Alternative data series may be prepared before running Populate, then activated inside the program to generate additional models. This strategy was used to examine the English demographic revolution in section 2. The program also facilitates impulse modeling, editing any data on the fly, without using an external editor, complicated instructions, or modifications of the source code. The If command is the key. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
If | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If | To activate or edit assumptions or data to compose a new projection tap I at the main menu. Any combination of assumption types--Age, Constant, Lifetable, or Variable--is permitted in a single model. Selecting If Age displays a layout on the screen to allow any of the age variables (fertility, mortality, migration or population age structure) to be activated in any year. Constant applies a constant adjustment factor to all years. Lifetable permits the selection of mortality and age structures from any of 200 model lifetables contained in the file "Populate.lif" (100 unisex and 100 female tables). Use If Variable to adjust values of any variable for specific years or periods. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If Age | This option permits one to switch any age structures (mortality, fertility, migration, or population) at any period in a projection. Thus, if say the mean age of childbearing is assumed to have shifted halfway through the projection period, this hypothesis can be incorporated into a model, by tapping If Age, then positioning the cursor at the desired year using the arrow keys and selecting the corresponding hotkey from the menu of age structures. Figure 10 shows the initial assumptions for England in 1539 with a shift to a late mean age of maternity (33 years) in 1559, and back to 31 in 1759. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 10. |
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| @@Figure 11 compares the gross reproduction ratio generated by this model with that of the baseline. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 11. | Gross Reproduction Ratios From Model A and Model K (Mean Age = 33, 1559; 31, 1759) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
@graph here | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| The If Age feature can be implemented for any year and any of the age variables either included in the program or read in as data from the input file. To toggle a selection off, position the cursor at the desired period and tap the corresponding age variable hotkey. Note that age conditions for the first year are set solely by the If Variable command as discussed below. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If Constant |
If Constant: Births Deaths Migration Population Restore "If Constant" adjustments can be for one or more variables and are applied to each year. To activate a constant adjustment, tap hotkeys: If Constant {B D M P} {type data value} <enter>. B adjusts Births for under or over registration 1.1 = increases births by 10% .9 = deflates births by 10% D adjusts Deaths for under (or over) registration Death factor<return> (same as births) M takes into account Migration 1.002 indicates 0.2% in-migration each period .998 = .2% outmigration P sets Population size to start a projection: Type starting population total <enter> R restores all the above settings to their initial values. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If Constant Migration |
Enter Migration Rate (0.998 = .2% outmigration per period) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| For example, to adjust a projection for constant in-migration of 0.1% per year, tap If Constant Migration 1.001<return>. This global adjustment will remain in effect for subsequent models, until changed or nullified (by simply tapping return at the "Enter Migration Rate" prompt instead of entering a rate). | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If Lifetable | This function activates lifetable parameters from any of Populate's 200 tables (female or both sexes combined, 4 regions and 25 levels ranging from life expectancy at birth of 20 to 80 years; Figure 12). A selected table may be used as the initial mortality assumption for the first year of a projection or it may be activated in any period when first selected by If Lifetable and then placed in the If Age array. Lifetables also may be selected, activated, viewed or (heaven-forbid!) edited by the If Variable Lifetable commands. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 12. | Lifetable Selection Screen
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| Once the lifetable function has been tapped (If Lifetable), select a region (West, South, North, East), then a level from the lifetable menu by tapping the respective hotkey (a = 20 years, i = 37.5, t = 57.5, and 1 = 75.0, etc.), and finally enter the desired growth rate for computing the appropriate population age structure. Growth rates are expressed in thousands (no decimal) and may range between +/- 50 (that is, plus or minus five percent per annum). Whenever a mortality pattern and age structure is invoked by If Lifetable the specified survival probabilities and age structures are automatically activated for the next model. The selection may be changed from the If Variable menu, which automatically appears after selecting a lifetable variable. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Model Fitting | When the initial mortality and age structures are unknown, the If Lifetable feature can be used to identify, by means of iteration, a set of better fitting initial constraints. The normalized mortality ratio (K, see below) is an indicator of the age-standardized intensity of mortality relative to the initial age and mortality constraints. The sum of squares of this ratio (K2) seems to be a robust measure of goodness of fit, when the birth and death series, initial population size, and initial growth rate of the population are held constant, that is only the initial mortality and age structures are allowed to vary. Better fitting models have lower K2s, when all other conditions--birth and deaths series and initial population size and growth rate--are held constant. The If Lifetable function is ideally suited for specifying and computing the range of models needed for fitting. K2 scores are reported at the end of each projection along with its title (use Options Model to review model titles and K2 statistics). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If Variable | This is the most flexible adjustment feature in the program. It is used to activate, view, or edit variables in preparation for a projection. Tap If Variable to display a menu listing the names of each of the currently available variables and their respective hotkeys. Active variables are indicated by an exclamation mark, "!" (Figure 13). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 13. |
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| Variable types | When the program is initiated, the first data series of each type (births, deaths, migration, total population, fertility age structure, pairs of survival probabilities, etc.) are automatically activated. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| When a selection is made from the If Variable or If Lifetable menus, the previous selection of the same type becomes dormant and the current one is activated for viewing, editing, or modeling. Thus as many as 48 variables may reside in memory, but only those that are currently toggled on by the appropriate hotkey on the Variable, Lifetable, or Age menus can be viewed, edited or used in projecting a model. For modeling purposes, migration and total population variables are considered to be the same type. Migration variables take precedence over population variables in the computation of a model. If both types are active at the moment of projection, the program automatically de-activates the total population variable. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Activating a variable | The first birth and death series read in at the beginning of a run are active throughout a session. Note, however, that, aside from the initial birth and death series, the program permits only one set of adjustments of each type (Population, Age, Migration, etc.) to be active for any specific year. Any adjustments invoked by a subsequent set of birth or death adjustments are to the corresponding initial series. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Replacing birth or death entries | Values from the initial series of vital events can be replaced entirely by activating an adjustment set which initially contains or is subsequently edited such that specific years have the equals operand followed by a value. Consider the "births" and "bcnst" data series from the example data file England.pop. The "births" series contains Wrigley and Schofield's estimates of the number of births per five year period from 1541 to 1871. The second series, "bcnst" (births constant), retains the original series through 1761 (multiples the original values by one), then for each subsequent period from 1761 to 1871 replaces the initial series with a birth rate of 32.3 per thousand. The data file looks like this: Births The W+S birth series for England ,541,528,583,508,517,581,536,576,... Bcnst observed births to 1761; .0323 to 1871, *1!1761, =.0323, =.0323 ! 1871 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Migration age | "Migrage" refers to the age structure of net migration. The programmed default weights are those for migrants to Stockholm in 1841, used by Wrigley and Schofield in their work: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| This variable may be edited like any others (If Variable), or one or more alternate migration age structure variables (name begins with a "G") may be placed in the data input, or xxx.csv, file. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mean age of maternity | "Bearxx" indicates mean age of childbearing. Four ages, 27, 29, 31, and 33 are included in the program: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Additional parameters | Once again additional parameters may be entered in the xxx.pop file (variable name begins with "Fnn", where nn = mean age). The values are weights used in distributing births by the ages of mothers. When this variable is included in a file, its values must sum to .2 for five year projections or 1.0 for annual projections. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Edit or View a variable | To view or edit a variable, toggle its hotkey, then tap function key 1, <F1>. The variable name and description will appear at the top of the screen along with a table of its operands and values at five year intervals. To edit values of a specific period, use the arrow keys to move the cursor to the desired year, tap the appropriate operand key (*-+=), type a value, and tap <enter> (Figure 14). When the entered value is greater than 1, the cursor will automatically advance to the next period. If less than one, confirm the edit by tapping any arrow key or <enter>. While the editor is active, tapping <enter> causes data to be accepted, and the cursor to advance. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| To exit the editor, tap <spacebar> or <esc>. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Figure 14. | Point and Press Editor | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Position cursor (tap arrow keys). Edit (tap *+=-). <space> to continue. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Operands and values | When the editor is selected, the values of the current variable are displayed and standard keyboard arrow keys are used to move the cursor around the screen. Tapping an operand (+-*= to add, subtract, multiply or set equal to, respectively), the insert key, or any number invokes a request for a value for the current period. The operand determines whether a value will replace an element (=) or whether an adjustment will be absolute (+-) or proportional (*). Thus entering *1.1 increases the value of the variable for the specified period by 10%, while +1000 would increase the value by one thousand. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Edited variables appear on the variable menu with a "_" to indicate that values have been changed. Once used in a projection, the edited values are written to the results file and the "_" disappears. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Interpolation | When birth, death or migration variables have zero values, they are replaced with logarithmic interpolations, provided that the bracketing values have identical operands. Thus, "=.035, 0, 0, 0, 0, =.030" becomes "=.035, =.034, =.033, =.032, =.031, =.030"; but, "=.035,0,0,*1.05" is interpreted as "=.035, =.035, =.035, *1.05" because of the different operands. Mix operands to avoid interpolation (see "bcnst" example in experiment 1). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Sequencing adjustments | Interpolations, if any, are computed first, then by period, and finally constant adjustments are made. Thus, a variable adjustment of 10% compounded by a constant adjustment of 10% for a specific period produces a total adjustment of 21%. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Undesirable results | When a projection produces unexpected results, first check the constant adjustment factors which define the model (see title of model on line 2 of the screen). If those are sensible, the problem probably lies with one or more of the period variables. To check this possibility, view the offending statistic in tables mode and identify the period in which the surprise appears. Then turn to the editor (If Variable {toggle hotkey of suspect variable} <F1>) to confirm that individual adjustment factors are as expected. For example, if one intended to set a birth rate at, say, 30 per thousand for a particular period, but actually typed "=030", the program would interpret this to mean "30" births (in hundreds, thousands, or whatever), rather than the desired rate ("=.030"). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Resist the temptation to blame unexpected results on programming bugs. When surprises occur, blow off steam. Curse the programmer. But before discarding the program or telephoning for help, carefully check the values of all active variables. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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4. Screen Display | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| The following commands have no effect on how projections are computed, but instead determine the type and manner of statistical results to be displayed or printed. When the screen becomes messy, Wipe it clear, then quickly re-display the desired statistics for specific projections. The fifteen display commands are examined in order of importance, beginning with the selection of statistics. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Axis Configure File Graphics Learn Models Note Print screen Restore Statistics Tables View Wipe Zoom | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Statistics | This command may be activated from the Populate, If or Options menus, by tapping S, to select Statistics to be displayed. Active statistics are indicated by "!": | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Statistics: !Pop !Birth !Death .Migr !Grr .Nrr .K !Life .0q .Cwr .Flux .Ydepend .Age .Sumage | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Statistics are computed for the mid-point of each five year period; see section 6 below for formulas. P = mid-point population B = crude birth rate D = crude death rate M = net migration rate G = gross reproduction ratio N = net reproduction ratio K = normalized death ratio L = life expectancy at birth 0 = probability of dying during the first year of life C = child-woman ratio (0-4/15-49) F = annual population flux (rate of change) Y = dependency ratio ({0-14, 65+}/{15-64}; if maximum age is less than 65, then numerator is 0-14 plus maximum age group) A = age groups (0,5,10+,15-44,30-54,50,25, etc.) S = sumage (cumulative percentage distribution, ages 0-4, 0-9, etc.) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Options Models | To review names and adjustments associated with each projection tap Options Models. When computer memory is exhausted projections are wrapped around to recycle memory allocated for the first projection. For example, with the English population dataset, the maximum number of projections which can be stored in memory is twelve. Thus, the thirteenth projection replaces the first and so on. This action only affects the display. Unless the file option is off, a copy of all statistics and adjustments is automatically filed to disc as each projection is made. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| View | To View results from current models (identified by letter), tap View and letter of desired projection. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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View Tap {AB...} L=List 1 stat/many models, else | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| View, List | Currently selected statistics are displayed (graphics or tables) with zoom settings. Several models may be displayed one statistic at a time, by first tapping "L", then selecting the desired models (!). Once the selection of models to be displayed is completed, tap <spacebar> to access the statistics menu and select the desired statistic. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Wipe | Wipe Wipes the monitor clear of graphics and/or text | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Zoom | Zoom contracts or expands the number of years to be displayed and the interval between displayed statistics (5, 10...25 years), within the bounds set by the year instruction at the beginning of the run. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Zoom Enter first year to graph xxxx-yyyy (or 1-t) <enter> Enter last year to graph xxxx-yyyy (or 1-t) <enter> Enter interval between periods (5, 10...25) <enter> | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Horizontal scale | With graphics, the horizontal scale depicts years from beginning to end (according to the current zoom setting, if any). The end year is automatically determined from the birth and death series, but both the beginning and end years may be changed by Zoom. Population projections are not affected by Zoom settings. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Axis | This command is only important for graphics, and in the rare instance when an axis must be extended (life expectancy goes beyond 100 years!) or contracted (life expectancy never exceeds say, 50 years). Vertical axes or scales are tricky because of the need to portray on a single screen, say, population in units of millions, life expectancy in years, rates in thousands, ages in percents, etc. Automatic scales are built into the program to facilitate a ready interpretation of each graphic. Moreover, to provide an exact indication of scale, the initial and most extreme values for each statistic are labeled on the screen. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Default Axes | The vertical axis of each statistic is set according to the following limits (minimum - maximum): | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Axis command | When adjustments substantially inflate the rate of population growth, Populate automatically computes a new scale adequate for viewing all population projections (and wipes the screen so that all graphics are displayed with the appropriate scales). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| The axis command is available for adjusting vertical scales. To activate the command, tap Options Axis. Select a statistic from the menu, then enter a scale adjustment factor. Factors greater than 1 extend the range (e.g. "2" for life expectancy would extend the range from 0-100 to 0-200 years); values less than one contracts (.5 for life expectancy, reduces the range to 0-50 years). The vertical axis may be changed for any of the statistics, except cumulative age distribution (which always sums to 100%). | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Configure | No longer needed for modern systems. (For pre-VGA systems, this option permits a rapid reconfiguration of the software for screen or printer displays. Use this option to change the adapter type (handy for Hercules systems to print text displays--<esc> Options Configure Adapter Mdpa View AB...<ctrl> <shift> <print screen>; to regain Hercules configuration tap <esc> OCAR) or to switch between color and monochrome displays--Options Configure Monochrome. Configuration changes are filed to disc when a session ends.) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Options Record (tutorials) | The recorder may be activated from the Options menu by tapping R, or at any time, by tapping !. Recording stops when ! or R is toggled off. The process may be interrupted by tapping \, and resumed by toggling \ again. When a recording begins, a title is requested for the lesson. Then at each keystroke, there is an opportunity to type an additional one-line prompt which will appear as the lesson is played back. When the recorder is on, always tap <spacebar> to move between menus or <esc> to jump directly to the main menu. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| .lrn files | Lessons are stored in the current file (xxx.lrn). Thus when England.pop is the active data file, the tutorials in England.lrn are automatically accessed. Lesson files may be edited by any word processor which produces standard end of paragraph codes. When the student is a relatively knowledgeable person, it may be desirable to simplify lessons. To simplify a tutorial, use a standard wordprocessor to access the xxx.lrn file. Replace several specific prompts from the same menu, by a single generic prompt beginning with a space <spacebar> or an escape <esc> and including all the commands which should be activated from a single menu. Thus, to activate models a e f g, these four commands (four paragraphs in the .lrn file), could be replaced by one generic command: "<space>select models a e f g then tap space". | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Note that there is only one learn file per .pop file. Use operating system rename or copy commands to manage more than one .lrn file per dataset. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Learn (tutorials) | Tap L (Learn) at the Main or Options menu to start a tutorial, a series of pre-recorded key strokes and prompts to guide the learner through one or more lessons. The student selects a lesson from a menu of options in the learn file, then taps <spacebar> to begin (or <esc> to skip) the tutorial. While a lesson is engaged, the command lines are expanded to provide additional prompting. Although the program insists that any recorded keystrokes be tapped in sequence, it also allows the student freedom to experiment (or to fail, but only the student knows)! If the lesson becomes fouled, tap <backspace> to step backward through the lesson, or <tab> to skip forward. To stop a lesson, tap L at the Populate or Options menu, or tap <esc><esc><esc>, rapidly in succession. It is always possible to escape from any menu in the program by tapping <esc> repeatedly. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Pasting from monitor screen | Any Populate image may be copies and pasted to another Windows program via the clipboard. Tap <PrtSc> ("print screen" near the numeric keypad). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
5. Data and Data Files | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Data types | Conventional projections are made from hypothesized demographic events--births, deaths, and migration--all classified by age. Populate assumes that only crude data are available, and that model age patterns can be used to overcome the lack of detailed age information. Specifically, the program uses the following types of data to construct a demographic balance sheet at five year intervals (the code used for identifying each variable type in a xxx.pop file is underscored): 1. Total population size at the start 2. Total births (or crude rates) by period 3. Total deaths (or crude rates) " " 4. Net migration (estimates, counts, or rates) 5. Fertility age structure (4 models in Populate) 6. Migration age structure (1 model available) 7. Mortality quotients or survival probabilities (200 models) 8. Population age structure (200 models times 100 at .1 intervals) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Only the first three data types are required in a .pop file. Nevertheless, whatever age data (real or hypothetical) are available for one or more periods can be used in Populate's projections. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Data files | Data must be placed in files in the currently open folder along with the program. Data input files should be prepared with a word-processor and saved without special formatting or printing features (ASCII characters only). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Enter DATA file name <return> (<return> = {England.pop}) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Results file | Before projections begin, an input data file name is requested. Enter any xxx.pop filename which exists in the open folder. Then, Populate requests an output, or results, file name. If no name is given, a default name is constructed from the input file name, so that xxx.csv becomes xxx.out for results. Results of each projection are filed in Basic comma-delimited format suitable for subsequent analysis by Lotus 1-2-3, Spsspc+, EXCEL, Stata, etc. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Enter results file name (<return> = {England.out}) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If the results file already exists, there is an opportunity to enter an alternate name. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Results file {England.out} exists. Delete? else. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Tapping D or <enter> deletes the prompted file, allowing the entry to be over-written by projections from the current session. Tapping any other key causes a request for a different file name. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Data Preparation | The program checks for seven lines of data: 1. title--must be line one. 2. year instruction (see below)--must be line two. 3. a birth series (rates or counts; there may be more than one set) 4. a death series (same as births) 5-6. 2 lines of survival variables (sets of probabilities from two life tables with similar mortality structures) 7. population age structure A note appears on the screen when one or more of these variables are not found in the data file. In fact only four lines are actually needed: a title, the year instruction, and birth and death variables. The remaining sets of parameters may be selected within the program from model lifetables, fertility schedules, and the like. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Data example | The data input file should contain instructions according to the following comma-delimited format (spacing and number of digits do not matter; only commas and <enter>). Each instruction consists of an identifier and its contents. The identifier may be a word or phrase, but must begin with a single letter key code (ybdmpqafg, as defined by data types above). The word becomes the variable name, and the phrase may contain any additional explanatory information (up to 70 characters); the identifier is terminated by a comma or end-of-line/paragraph mark ("¶" in the examples below; with conventional word processor tap <enter>). Identifier, Contents (each item separated by commas) Example (in italics from the file England.pop) 1. "Any title" (must be the first line) England Wrigley & Schofield's data + Lee's qxes 2. Year, a. T1 (begin year), b. Tm (end year), c. Sex (F = Female data; else any other value = unisex) d. Initial Population size (use same units as counts of births, deaths, migration, etc.), e. Mean Age at Childbearing (27, 29, 31, or 33), f. number of age groups (>10<22; 21 most precise, slower projection; 17 is recommended where life expectancy at birth exceeds 40 years); example: year,1539,1873,U,2724, 31,11 3. Qx, Mortality quotients 0, 1, 5...n, 1-(T>n/Tn) qxlee mortality quotients used in 1985 Pop Studies article¶ .255,.145,.050,.038,.049,.059, .065,.072,.081,.092,.107, .2568 4. Qx, Adjacent Qx 0, 1, 5...n, 1-(T>n/Tn) qxadj also from Lee from an adjacent life table¶ .214,.117,.041,.032,.041,.050,.055,.061,.068,.078,.092, .24935 5. Age, Population Age Structure, 0-4, 5-9, ...n+ agews age structure in 1541 estimated by Wrigley and Schofield¶ .13,.11,.10,.09,.09,.08,.07,.07,.06,.04999,.15001 6. Births, Number of Births at T1, T5,...Tm. (Erratic spacing produces desired results). Births estimated by Wrigley and Schofield , 541, 528¶ 583,508,517,581,536,576 ¶ 617,623,635,625,690,727,713,717,766,745,777,800,825,794¶ 700,763,688,761,738,744 ,742 ¶ 799,779,783,836,809,753,846,883,895,895,967,916,943¶ 974,983,1041,1075,1156,1222,1253,1369,1512,1588,1633,1877¶ 1951,2232,2341,2414,2368,2509,2687,2782,2994,3189, 3427¶ 3675,3865 ¶ The following example, when active, causes the original birth series to be multiplied by 1 from 1539 to 1761, then in 1766, replaces the original series by an annual rate of 32.3 per thousand, which continues through 1871. Operands are discussed in the editing section (above); the "!" convention below in special data features: Bcnst projects average birth rate for 1661-1761 forward to 1871¶ *1!1761, =.0323, =.0323 ! 1871 7. Deaths, No. of Deaths at T1, T5,...Tm. Note the end of line marker ¶ (but no comma) after "Deaths", "523", etc. below. Use one delimiter (either "¶" or ",") but not both to separate data items. Deaths Wrigley and Schofield's estimates ¶ 407, 445, 391, 525, 490, 387, 399, 383, 392, 474, 523¶ 500, 505, 485, 576, 586, 551, 663, 589, 670, 728, 632¶ 644, 757, 676, 786, 739, 673, 873, 764, 706, 719, 669¶ 711, 712, 694, 840, 860, 920, 756, 880, 760, 755, 776¶ 882, 881, 889, 858,1015, 985,1014,1092,1173,1144,1263¶ 1359,1385,1451,1461,1573,1665,1828,1907,1989,2071,2289¶ 2356¶ Dcnst projects 1661-1761 average to 1871¶ *1!1761,=.0274,=.0274!1871 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Note that data items may be prepared in columns or scattered freely, but in any case, each item must be separated by a single delimiter (either a comma or end of line or paragraph mark). | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Data limits | A total of 40 variables may be included in a data input file (alternative birth/death series/rates, birth or death adjustment factors, migration rates, fertility or migration age structures, etc.). When additional lines or variables are present in the file, the program automatically classifies the data by type for use whenever activated by If Variable or If Age (see above). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Data typing | Each instruction begins with an identifier or variable name (BDMGTPFA, for Births, Deaths, Migration, miGration age structure, Total population, survival Probabilities, Fertility age structure, and population Age structure, respectively) which is used by the program to classify variables. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Optional data types | In addition to the types discussed above, the program recognizes and uses the following optional types of data: fertility age structure (F), migration age structure (G), migration (M), and total population (T). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fertility age structures | The age structure variable label begins with "F" followed directly by the mean age of childbearing. The values for ages 15-19...45-49 should sum to 0.200. They indicate weights to be assigned to age groups in distributing births to women of age 15, 20,...45-49.
Example: F31 , .008,.032,.054,.05,.034,.018,.004 The following example indicates a mean age of 28.48 to be activated in 1935. The annotation will be ignored by the program, and the weights (.023, etc.) correctly interpreted: F28.48 !1935 Mexico Mier y Teran's est. p. 547¶ 0.023, 0.050, 0.050, 0.037, 0.024, 0.014, 0.002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Migration age structure | Migration age structures are recorded for ages 0-4,...maximum age group and should sum to 1.00. Example: Gstockholm age structure of net migrants to Stockholm in 1841¶ .065,.045,.040,.100,.200,.200,.200,.075,.03, .03,.015 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Migration estimates | Migration indicates estimates of net migration and may be reported as rates (*1.001 = 0.1% net in-migration of total population in a single period) or absolutes (same units as total population above). Examples: MigrW+S Wrigley and Schofield's estimates of net migration for England¶ -18,-20,-22,-19,-17,-18,-21,-23,-26, -31, -35, -36, -36¶ -34, -30, -25, -22, -24, -24, -31, -40, -49, -58, -63, -62, -55¶ -45, -35, -26, -19, -18, -20, -22, -25, -27, -28, -28, -28, -26, -24¶ -25, -26, -28, -31, -35, -35, -31, -26, -22, -17, -15, -18, -23¶ -28, -34, -41, -50, -63, -78, -90, -102, -115, -124, -122, -109¶ -102, -117 MigrLee Lee's long swings in English out-migration¶ *.9985,*.9985!1689,*.99915,*.99915!1799,*.9998,*.9986!1859¶ *.999!1871 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Total population | The total population variable sets a population target to be realized at the beginning of the corresponding year. Differences between the target and computed population size are automatically attributed to migration, and migration rates computed accordingly. In reporting estimated migration results based on total population, a migration estimate is given only for the years in which there is a population estimate, but the rate applies to the entire set of periods bracketed by estimates. See special conventions below. Example: TpopLee population estimates brought together by Lee in 1985, 2724!1539¶ 4800!1694,8400!1799,21000!1871 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Lifetable | This data type activates mortality and/or age structures from the model life tables at the beginning of a session. The Lifetable instruction has five elements: region, level, growth rate, year to activate mortality structure, year to activate age structure. If the year instruction specifies female, then female lifetables and age structures will be retrieved. Region: west, north, south, east Level: life expectancy at birth of 20-77.5 years growth rate: -50 to +50 per thousand population mortality year: any year (if greater than maximum or less than minimum, then data are retrieved, but not activated) age year: same as for mortality Example: Life,west,37.5,8,1541,1541 - activates both mortality and population age structures in 1541 for a west population with a life expectancy at birth of 37.5 years and an annual growth rate of 8 per thousand. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Special data conventions. | Total population, migration, births and deaths absolutes should be reported in the same units (hundreds, thousands, ones, etc.) or as rates. If birth or deaths are less than 1.0 but greater than zero, they are interpreted as crude rates rather than totals and projections are computed accordingly. Rates and absolute values may be inter-mixed. If population age structure values are less than one (e.g., .123), they are interpreted as percentages and should sum to 1.0. Zero values for migration, births, or deaths are replaced, whenever they are active, with logarithmic interpolations between known points. Zero total population provides an alternative treatment. No interpolation occurs. Instead the approximate rate of net migration is estimated to achieve a specified population size for intervals between estimates. For an example, project England.pop with all migration variables off and "Tpoplee" active. The rates computed for 1694, 1799 and 1871 would apply to the intervals 1541-1694, 1695-1800, and 1801-1873. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| !data | To reduce excessive null values from data input, the "!" convention is used to assign values to an exact year. For example, the "bcnst" variable, used to specify the constant birth rate for model f (see data example "6." above), multiplies the observed birth counts by one from 1541 through the 1761, then sets the birth rate to 32.3 per thousand through 1871. Once this or any other type of data has been read in, the editor can be used (If Variable {select variable} <F1>) to fine tune any estimate, count, supposition, variable, or hypothesis. To project into the future, set a rate for the last observed period, then a target rate for the last desired period. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Age variable!year | Any age variable may be automatically invoked for a particular period from within the data input file by following the variable name with "!" and the corresponding year. Thus, "F28.48 !1935" (see fertility age structure above) activates this fertility variable beginning in 1935; it remains in force during the projection until deactivated from the If Variable menu. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| End | When encountered in a .pop file, the "End" instruction completes the data reading routine. Instructions beyond the end statement are not read and thus cannot be activated. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mexico, 1500-2000 | The Mexico.pop file suggests the program's flexibility in reading data and computing models as well as projecting into the future. To Populate Mexico, start the program and request Mexico.pop as the data file. Project model a to see, according to one scenario, the evolution of five centuries of Mexican population. Upon displaying the cumulative age distribution for the entire set (tap Statistic Sumage View), you will observe that the demographic holocaust of conquest remained only a faint echo on the population age structure of the late seventeenth century. Even under the most extreme circumstances, vital rates prove to be more important than initial states. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Checking data | Before any computations begin, data are always checked for consistency as they are read into memory. If unexpected patterns are found, a message is displayed at the bottom of the screen. Once this step is complete and before the first projection begins, a menu is displayed to permit editing of any variable, activating a lifetable (see If Variables above), or setting any of the age parameters (If Age). After adjustments are complete or a desired set of variables activated, if any, tap <spacebar> to initiate the projection. Whenever the file England.pop is requested from the start-up menu, the first model is computed directly without further ado. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| For additional information and complete specifications, see the File and Data help screens or examples in England.pop and Mexico.pop. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Female only projections | When "F" is specified on the year instruction, Populate shifts to female only mode. All input data--population size, births and deaths (counts or rates), migration, etc.--refers solely to females. When lifetable parameters are requested by If Lifetable, female values will be retrieved. Similarly, statistical results, including reproduction ratios, refer to the female population. Normally, Populate assumes equal sex ratios at all ages. When sex ratios are markedly unequal during the child bearing years--due to differential mortality or migration--more reliable fertility estimates may be computed by projecting the female instead of the total population. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Results | Results written to the output file consist of two information lines, demographic statistics for each period, and specifications for each projection: Information: Title, Date, Time Projection: Settings for Initial Population and adjustment factors, if any. Whenever a variable is edited then used in a projection, all its values are written to the results file in Populate's comma-delimited format. Names of active variables are also positioned in the results file, immediately preceding the title of the model. Statistics are written to the results file, one line for each year (quinquennium for five-year projections), as follows: year, beginning and mid-period population, crude birth, death, natural increase, and net migration rates, Gross reproduction ratio, Net reproduction ratio, K (normalized death ratio), life expectancy, infant mortality rate, percent of population aged 0-4, 5-9, ..., maximum age group | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
6. Miscellaneous | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Enhancements (Versions 2.0-2.9) |
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| Thanks to: | Renee Holoien (Project Woksape) provided facilities and encouragement.
Ron Lee developed the inverse projection method and suggested important improvements to Populate. Robert Rowland offered helpful programming hints in his program, Migsmam, which he developed to compute singulate mean age at marriage adjusted for migration. Robert Jackson tested Populate with trying data from a large number of eighteenth and nineteenth century California missions. George Alter suggested improvements for the variable, lifetable and tutorial screens. Steven Ruggles relentlessly searched out errors and annoyances. James Vaupel provided simulated data to calibrate the program. Steven McCaa, after Oedipean assaults on the program, made valuable suggestions for screen design, menu style and subroutine flow. and thanks to students who asked questions or made suggestions. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Problems with Populate? | Please send a note relating as much detail as possible (screen prints of all active variables and unexpected results, etc.) to: Robert McCaa, Department of History, University of Minnesota, Social Sciences 614, Minneapolis, MN 55455 USA Email: rmccaa@umn.edu | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Shareware | Populate is distributed as shareware. A copy of the program is available on the web at: http://www.hist.umn.edu/~rmccaa/software | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Go forth and | Populate--cautiously! The quality of a projection rests on data accuracy and the validity of one's assumptions. There should be no surprise that projections based on complete data and complex algorithms will produce more reliable estimates of fertility, mortality, and age structure. Where demographic knowledge is slight and the data few, Populate projects a beams of light, if only faintly. Its scope and intensity can be adjusted by experimenting with the data and assumptions on which projections are based. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Formulas | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| "Normalized" death rate (k) | Where, L0x = total number of person-years lived between exact age x and x+5 in the stationary population µ = total number of 5 year age groups Þ = open ended age group (e.g., 55+, 75+) qx = the death rate for age x, 1-l0,x+5/l0x, where lx = persons alive at exact age x Ntx = population age x, at beginning of interval t Nt0 = number of births during interval t. Where S"x is the survival rate from limiting life table (life expectancy at birth = 80) at age x and S'x is the survival rate from life table 1 at age x, dx = S"x - S'x And, kt = (Dt- (qx*Ntx))/( (dx*Ntx)), at time t, x = 0 to Þ K = (kt2) Then, ptx = 1-(qx+kt*dx) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If, pt0 < .1, pt0 =.1 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If, pt0 > 1., pt0 = pt-5,0*.9 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| If, pt0 > .995, pt0 = .995 And, Nt+5,x+5 = Ntx*ptx Lt0 = 500000*pt0 Ltx = Lt,x-5*ptx, for x = 5 to µ LtÞ; = (Ltµ*ptµ)/(1-ptµ) et0 = Ltx/100000, x = 0 to Þ Nt+5,x+5 = Ntx*ptx | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Gross reproduction ratio | Where, a is the lowest age at childbearing and b, the highest And, fx is the normalized age pattern of fertility, for ages x a to b, such that fx = .2. Then, Ft = ((Ntx +Nt+5,x)*fx), x = a to b gt = (Nt0/Ft)*.4 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net reproduction ratio | Where, M = mean age of childbearing i = TRUNC(M/5), 5 year age group for mean age at childbearing c = (M-(i*5)/5 Then, nt = gt*((Li-(Li-Li+1)*c)/500000) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mid-period population | Tt+2.5, and crude rates Tt+2.5 = EXP(LOG(Tt)+LOG(Tt+5))*.5) CBRt = Bt/Tt+2.5 CDRt = Dt/Tt+2.5 NMRt = Nt/Tt+2.5 CWRt = Nt0/Ntx, x = a to b | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net Migration | Where, mx is age pattern of migration M = estimated net migration for time t Then, Ntx = Ntx + Mt*.5*mx Nt+5,x = Nt+5,x + Mt*.5*mx | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net Migration adjustment | Where, Mtz = adjustment for Migration at time t M0z = adjustment for Migation for every time t Mtf = migration adjustment factor type at time t When, Mtft = Mtz*Tt Else Mt = Mtz And when, M0z < 1.5 and M0z > 0, Mt = Mt * M0z Else Mt = Mt + M0z | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Total population adjustment | Where, Ttf = "*", Tt = Tt * Ttz Ttf = "=", Tt = Ttz Ttf = "+", Tt = Tt + Ttz Ttf = "-", Tt = Tt - Ttz Then, Tt = Tt + Mt*.5 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Birth adjustment | Where, Btf = "*", Bt = Bt * Btz Btf = "=", Bt = Btz Btf = "+", Bt = Bt + Btz Btf = "-", Bt = Bt - Btz | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Death adjustment | Substitute D for B in Birth adjustments | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Converting estimated crude rates to counts of births and deaths |
Where Bt < 1. And Dt < 1., Rt = EXP((LOG(1.+Bt-Dt)))*2.5) Where Bt < 1. And Dt => 1., Rt = EXP((LOG(1.+Bt-(Dt/Tt)*.2))*2.5) Where Bt > 1. And Dt < 1., Rt = 1. Then, Births from birth rates: Bt = Tt*Bt*Rt*5 Deaths from death rates: Dt = Tt*Dt*Rt*5 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Interpolation of birth, death, or migration counts or rates |
Where, k = births, deaths or migration Atk = adjustment value for variable k at time t Otk = operand for value of variable k at time t r = previous time when Atk <> 0; r < t s = next time when Atk <> 0; s > t When, Atk = 0, then Otk = Ork If Ork = Osk, Atk = Ark+((EXP((LOG(Ask)-LOG(Ark))/(s-r))))*(t-r) If Ork <> Osk, Atk = Ark | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Migration estimated from total population | Where, p = total population When, A.p is active, and Atp > 0 Then, approximate annual migration rate for t Mt = (((Tt-Atp)/(t -r))/((Tt+5+Atp)*.5))/5 And, total population for t becomes, Tt = Atp | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
7. Glossary. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Explanation of symbols. | Commands begin with upper case italics characters. Keystrokes required to activate a command consist of a series of words beginning with these characters, listed in order from the main menu. Commands for the corresponding help screens containing additional information are fully italicized. Named keys are bracketed by carets <>. Tap the key to carry out the command. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <esc> | Escape to the main Populate menu. Tap the <escape> key. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <esc> <esc> <esc> | Escape from any tutorial that may be active or from any menu. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <enter> | Accept the requested data. Tap <enter> or <return>. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <spacebar> | Move one space toward the main menu. Tap <spacebar>. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <tab> | In learn mode, tab forward in the current help screen or lesson. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <backspace> | In learn mode, move one step backward in the lesson. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <F1> | Edit the currently selected variable. See edit. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <PrtSc> | Paste currently displayed screen to the Windows clipboard. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <!> | Turn the recorder on. See record. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <\> | Pause the recorder. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 0q | mortality quotient for the year of life following birth. Statistics. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Active | any currently selected feature or variable, "!", used in projecting a model. If Variable. Basics Options If Adjust Edit View | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Adapter | For pre-Pentium machines only. The hardware used to display information on the screen. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Age | Age statistics estimated for each period. Statistics. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Age | variables (suppositions) about age structure of mortality, migration, fertility, or population. There must be at least 11 age groups for mortality, migration and population variables (0-4, 5-9...50+), and no more than 16 (...75+; desirable when life expectancy at birth exceeds 40 years). Fertility ages require only 7 values (15-19, ...45-49). Age variables may be activated at the beginning of a model (If Variable...) or at any specified year(If Age...). If Adjust Edit | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Axis | Extend or contract the vertical axis for displaying any statistic. Tap Options Axis, select a statistic, then enter an adjustment factor. Values greater than 1 extend the range; less than one contract it. To contract the range of birth rates from 0-99 to 0-33, tap O A B .33<enter><esc>. To Restore original axes, tap O A R. Options | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Birth | Specified series of births, or birth rates, as read into the program from the input data file. Data Files Xample | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Child/woman ratio | See Cwr. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Color | automatically configured by Windows. To change color from within Populate, select Options Configure Color. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Common Commands | 15 actions or functions invoked from the Main, If or Options Menus: File Graphics Help IF Models Note Options Quit Record Statistics Tables View Wipe Zoom | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Configure | the program for text or graphics adapter card, or change color or monochrome settings. Options Configure Adapter Color Monochrome. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Constant | set constant demographic parameters to be applied to a model. Birth rate, Death rate, Migration, or initial Population. This feature permits across-the-board adjustments to be quickly specified. If Constant... If Adjust | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Continue | Tap <spacebar> or an unassigned key at any menu to continue to the next menu. <enter> is synonymous with <spacebar>, except when editing, where <enter> moves the cursor forward without continuing to the next menu. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Core menus | Three main menus: Populate, Options, If. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Cwr | child woman ratio statistic: children aged 0-4/women aged 15-49, computed from age estimates for each year or period. Statistics. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Data | information used to calculate a demographic model. A Populate data file consists of title, year instruction line, series of births and deaths (either counts, estimates, or rates); optional instructions include survival probabilities, net migration estimates (or rates), age structure, fertility structure, or migration age structure. As many as 40 variables may be referenced in a single file. The default file name is xxx.pop. Data Files | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Death | series of deaths (counts or estimates), or annual death rates (less than 1.0, greater than 0.0), read into Populate from a data file. Data Xample | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Dependency Ratio | Population aged 0-14 + population aged 65 years or more (or maximum age group when less than 65) divided by population 15-64. Statistics Ydepend. Statistics | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Edit | variables. To edit a variable, tap: If Variables {toggle the hotkey of the desired variable} <F1>. Then move the arrow keys to the desired period, type in any operand and value, and tap <enter>. Tap the <spacebar> to exit the editor. Edit | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Escape | Tap the <esc> key to escape directly to the main menu. When in Learn mode, tap <esc> repeatedly to escape from a lesson (or tap L at the main menu). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| File | When on, results of each projection are automatically written to the output file. Options File. Options | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Flux | Annual rate of change per thousand mid-period population. Statistics. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Graphics | plot demographic statistics on the screen. To activate graphics, at the main menu tap G. Tap G again to turn graphics off (and tables on). When graphics are on "!", tap T to display statistical tables. Graph View | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Grr | gross reproduction ratio, a fertility statistic: total births in each year or period are distributed according to weights from the currently active fertility schedule, summed, and divided by the total female population aged 15-49. Four age schedules are included in Populate: mean age of childbearing of 27, 29, 31 and 33 years. Any one of these may be activated for any particular period. Statistics | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Help | definitions of terms available at any menu, by tapping H. Tap H again for a menu and description of all Help screens. Tap <tab> to skip a screen, <spacebar> to return. Help | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Hotkey | first letter of a command word, which when tapped triggers the corresponding action. Tap <spacebar> to continue, <esc> to escape to the main menu. Tap H, N, Q, W at any time for Help (explanation of commands), make a Note in the results file, Quit the program, or Wipe the screen. <ctrl> <shift> <print screen> prints the current screen display on a dot-matrix printer. ! - toggles the recorder on and off. \ - pauses the recorder. Basics | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| IF | begin a sequence of menus to activate or edit variables and specify conditions of a model or projection. If Adjust | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Infant mortality rate | Number of deaths under one year of age per 1000 annual births. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Install | For pre-Pentium machines--no longer needed. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Interpolation | null data values of active birth, death, or migration variables are estimated as the logarithmic average between two specified data points. This is the optimal solution for all variables except total population size, where population totals are simply reset, and any difference between projected and set is attributed to migration. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| K | relative mortality variability; minimize K2 to obtain best fit of model age structures. Statistics. Options Model | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Learn | begin a tutorial with recorded lessons from a xxx.lrn file. The command screen expands to permit an additional line of instructions to be displayed with each menu. Learn | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Life | life expectancy at birth computed from the total number of deaths for a year or period and distributed according to weights derived from the difference between survival probabilities for two life tables of the same region. If Lifetable. Statistics. If Adjust | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Lifetable | survival probabilities for 25 mortality levels (life expectancy at birth from 20 to 80 years) and four regions (West South North East). If Lifetable (activates the selected mortality and age structure) or If Variable Lifetable (activates and allows one to view or the expert to edit lifetable values.) Editing is not recommended. Instead, prepare survival probabilities and include in the data file. If Adjust | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Migration | net migrants, or migration rates, as read into the program from the input data file. "-nnn" indicates net outmigration, and +nnn, in-migration; "*nnn", migration rate. When *nnn is less than one, the net migration rate is outward; *nnn greater than one signifies net in-migration. Statistics. If Variable... Data If Adjust. See out migration. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Model | a projection defined by active variables (initial population size, birth and death series, migration estimates, and any age structures) and constants. Statistical results include population size, crude birth and death rates, life expectancy, gross reproduction ratio, etc. To review a list of models and their specifications, tap Options Model. Statistics Results | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Net Reproduction Ratio | The proportional population change per generation; calculated here as the product of the gross reproduction rate and the probability of survival to the mean age of childbearing. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Note | type a note to the current results file. Available at any menu, but not while calculating, editing, or entering a response. Basics | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Operand | See adjust, edit, data. Data Adjust | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Options | menu to change the statistics displayed or the way information appears on the screen. Options | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Out migration rate | estimates or counts of out-migrants in each year or period, distributed according to age weights either from data input or those from within the program. When the number of out-migrants for an age group exceeds one-half of the number of people for that age group, a message appears at the bottom of the screen. Except in the most mobile populations, one would normally expect "migrations" of such magnitude to be due to a typing mistake, either of some value or its operand. Corrective action: review the statistical results for the year or period in which this occurred to pinpoint the problem (too few births, too many deaths or migrants). Carefully check the values of each variable used in the projection (including operands). Data Edit Results | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Output | results written to a disc file. Results Files | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Pause | interrupt the recording of a tutorial's key strokes, by tapping <\>. Tap <\> again to resume. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Populate | calculate a model using the currently specified If conditions: birth and death series, life tables, age structures, constants, etc. Populate Basics | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Populating... | results are being calculated for the current model. The keyboard is turned off while calculations proceed. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Population | totals at the beginning of a model (If Constant) or mid-year or period estimates. Statistics Results | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| <PrtSc>: Paste to clipboard | Paste monitor image from the screen to the Windows clipboard. Tap <PrtSc>. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Quit | close the results file, stop the session, and exit Populate. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Qx | age specific mortality quotientes from a life table. When included in a datafile, two sets must be present (for ages 0, 1-4, 5-9...last age group). Life tables may also be selected from the 200 models (96 unisex, 96 female) included in the file Populate.lif. If Adjust Data | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Record | procedure to create a lesson, that is, record a series of commands or keystrokes and save them to file xxx.lrn. Use record to prepare a tutorial. Begin recording a lesson, by typing <!> or Options Record. Finish a lesson by typing <!>. As each hotkey is stroked, type a brief message or additional prompt, which will appear as the lesson is played back by the student. To pause recording tap <\>, and <\> again to restart. Use <spacebar> to return from a menu, or <esc> to jump to the main menu. To reduce the number of prompts at playback where multiple strokes are desired from a single menu, pause the recorder, tap the desired strokes, start the recorder again, tap <spacebar> and type a single message explaining all the expected strokes. .lrn files may be edited using any editor which does not place odd formating commands in the file. Options. Learn | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Reinstall | No longer needed for Windows systems. Pinstall Install. Ynstall | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Restore | values of data constants or axes to their initial settings. If Constant Restore. Options Axes Restore. If Options | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Space | Tap the <spacebar> to continue from one menu to another. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Sumages | Cumulative age distribution. Statistics. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Tables | display demographic statistics on the screen as tables. To display graphics on the screen (on systems which support this), tap G. To view the statistical results from many models, select View List {select desired models} <spacebar> {select desired statistics}. Options. View Results | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Toggle | Turn a variable or option on or of by tapping its hotkey. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Universal keys | may be activated at any menu: <Esc>, <spacebar>, Help, Note, Quit, Wipe, {<ctrl><shift><print screen>}, <!>, and <\>. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Variable | an array of demographic information (births, deaths, age patterns of fertility or mortality, migration, etc.). Variables are used to calculate results for a model specified by If Variable and If Age. Active variables are marked," !". If Adjust Data Files Edit | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| View | display one or more models or statistics on the screen. View | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Wipe | clear the screen of all information and display the next menu. Basics | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Ydepend | See dependency ratio. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Zoom | change the display so that data are displayed from xxx to yyy at intervals of zzz (5-50 years). Options. View | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Install | Populate with Pinstall no longer needed with Windows systems. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| For all systems, first | Copy or Unzip all files from the Populate disc to the Populate folder. Files for Help (Populate.hlp), life tables (Populate.lif), and installation settings (Populate.ini) must be readily available in the Populate folder. Otherwise, a message appears on the screen, and the program stops. The solution: copy all files from the original to the work folder. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Disc space | Populate reads data and automatically writes results to disc files as projections are made. However automatic filing may be toggled off, by tapping Options File from the Populate command line. Should disc space become exhausted, the program notes the condition on the screen, and completes the current projection. No further information will be written to disc. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Projection Limits | The program accommodates up to 640 years of population history with as many as five projections immediately available for display as tables or graphics. When the time series under examination consists of only 150 years, up to thirty projections can be instantaneously examined. When the limit of available computer memory is reached, the program sends a note to the screen, then simply recycles the space allocated to the first model, and projection continues. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Performance: | Computational speed is no longer a concern with twenty-first century PCs, although it was when this program was first developed. Projections are now instantaneous, when they used to take as long as 2 minutes. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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The Population Age Structure of England, 1541-1871 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||