Integrated Public Use Microdata Series International
census microdata for social and economic research
Sampling

IPUMS-USA
Sampling practicesIPUMS Design: Introductory essays:
  • Sample Design (Chapter 2).
  • Sampling Errors (Chapter 3).
  • IPUMS International
    For private households,
  • the preferred sampling unit is the dwelling.
  • Group quarters are defined as:
  • institutions and other units with 31 or more persons.
  • Three strategies
    Where records are ordered geographically:1. Sample every Nth dwelling or household.
  • For group quarters, the preferred sampling unit is every nth family with associated dwelling characteristics.
  • This systematic sample is equivalent to an equal-probability sample with full geographic stratification.
  • This maximizes precision without the need for a complex sampling scheme.
  • Using the dwelling as the sampling unit reduces the individual-level precision due to clustering.
  • Geographic stratification helps make up some of the loss.
  • If not ordered geographically:2. Sample randomly
    3. Sample by some dwelling level characteristic:
    For example, the United States Census Bureau uses the following scheme:
  • Race of Householder:   White, Asian & Pacific Islander or Other; Black, American Indian, Eskimo or Aleut
  • Origin of Householder:   Spanish, Non-Spanish
  • Tenure of Housing Unit:    Owner, Renter
  • Family type:
       Family with Own Children Under 18
       Family without Own Children Under 18
       Other Household (non-family)
  • For Group quarters only:    Inmate, Other GQ persons
  • All the combinations of these characteristics are used to define strata.
    In effect, sampling is done separately for each stratum within each geographic area.