Colombia: 1973, 1985, 1993
Kenya: 1989, 1999
Mexico: 1970, 1990, 2000
United States: 1960, 1970, 1980, 1990
Vietnam: 1989, 1999

Colombia 1973-1993: Persons age 5+.
Kenya 1989: Persons age 6+.
Kenya 1999: Persons age 5+.
Mexico 1970: Persons age 6+.
Mexico 1990-2000: Persons age 5+.
United States 1960: Persons age 5+.
United States 1970: Persons age 3+.
United States 1980: All persons.
United States 1990: Persons age 3+.
Vietnam 1989-1999: Persons age 5+.

SCHOOL indicates whether or not the person attended school at the time of the census or within some specified period of time prior to the census.

The age of persons to whom the question applies varies across the samples. Vietnam and Kenya distinguish between those who never attended and those who had left school.

For most samples, school attendance was determined as of the time of the census. The U.S. censuses determined school attendance with respect to a specified period of time before the census - typically several months to a year prior. The Kenyan samples suggest a longer timeframe as well, referring to a person's attendance "this year."

In all countries the nature of the inquiry on school attendance appears aimed at designating those persons attending schools with a normal program of study leading ultimately to a succession of grades or levels.

In 1973 and 1993 the question applied to persons 5 years and older. 1985 had no age universe, but a 5-year age limit has been imposed to make the sample comparable to the other Colombian datasets (i.e., persons under age 5 are coded "not in universe"). The question specifically refers to a person's enrollment status at the time of the census.

Between 1989 and 1999, there is a one-year difference in the age of persons to whom the question applies. Attendance is in reference to full-time education in at formal educational institutions. Both censuses stated that attendance means "persons attending school this year."

In 1989, persons in group quarters (i.e., travelers and short questionnaire respondents) have a missing response for schooling.

There is a one-year difference in the age of persons to whom the question applies. The question refers to status at the time of the census.

The age universe for the question changes among the U.S. samples, with 1980 asking the question of all persons.

For all samples, a person was to have attended or been enrolled in school since February 1 of the census year in order to be counted as having attended school.

The definition of "school" varied as follows:

1960: any kindergarten or elementary school, and any schooling leading toward a high school diploma or college degree. Nursery school, business or trade school, and adult education classes were not to be counted.

1970: any educational nursery school (not simply custodial child care), kindergarten, elementary school, and any schooling leading toward a high school diploma or college degree.

1980 and 1990: any nursery school, kindergarten, elementary school, and any schooling leading toward a high school diploma or college degree. (Other types of schooling counted only if a regular elementary school, high school, or college would have accepted it for credit.)

Affirmative answers to attendance are with respect to persons currently attending school at the time of the census.