Colombia: 1973, 1985, 1993
France: 1962, 1968, 1975, 1982, 1990
Kenya: 1989
Mexico: 1960, 1970, 1990, 2000
United States: 1960, 1970, 1980, 1990

Colombia 1973-1993: Employed persons and persons seeking a job who have worked before, age 10+.
France 1962-1968: Employed civilians, age 14+.
France 1975: Employed civilians, age 16+.
France 1982-1990: Employed civilians, age 14+.
Kenya 1989: Employed persons, age 10+.
Mexico 1960: Persons age 8+.
Mexico 1970: Persons age 12+ who worked at least one month during the last year, regardless of their status at the moment of the census.
Mexico 1990-2000: Employed persons, age 12+.
United States 1960-1970: Persons age 14+ who have worked in the past 10 years.
United States 1980-1990: Persons age 16+ who have worked in the past 5 years.

CLASSWKR refers to the status of an economically active person with respect to his or her employment, the type of explicit or implicit contract of employment with other persons or organizations that the person has in his/her job. In general, the variable indicates whether a person was self-employed, or worked for someone else, either for pay or as an unpaid family worker. CLASSWKR is related to EMPSTAT, which is used to define the universe in many samples. Class of worker is sometimes referred to in other sources as "status in employment."

The first digit of CLASSWKR is comparable across samples. The second and third digits preserve additional information available for some countries and years.

The universe of persons to whom the question applies varies across the samples. For most of the censuses, the question applied to employed persons. Employed persons include people at work, or not at work but with a job, at the time of the census.

Some samples have extended and/or more complex universes. For the Colombian censuses, for instance, persons seeking a job but having worked in the past reported this information relative to their former jobs. For Mexico 1970, persons having worked at least one month during 1969 reported their class of worker even if they were not employed at the time of the census.

The Colombian censuses do not pose problems in terms of universe comparability. The 1993 census combined white and blue collar employees, while in the two previous censuses they were separated.

There are no major problems of comparability in terms of universe and category availability. In fact, the class of worker variable used for the French datasets was already integrated across the samples by the French statistical agency.

NOTE: Only a small fraction of the workforce reported its class of worker.

The universe for CLASSWKR varies considerably among the Mexican samples. Mexico 1960 asked the question of all persons age 8 and older. In Mexico 1970, the question was asked of all persons age 12 and older who worked at least one month during 1969, regardless of whether or not they had a job at the time of the census. This is an important difference from the 1990 and 2000 censuses, which applied the question to persons employed at the time of census.

The CLASSWKR universe for 1960 and 1970 includes person age 14+ who had ever worked in the previous 10 years, regardless of their current employment status; for 1980 and 1990, the age cutoff is 16+ and respondents had to ahve worked in the past 5 years. All years distinguish between various classes of public (government) and private employment and identify unpaid family workers. The 1970, 1980, and 1990 censuses distinguish between employers and other self-employed persons whose businesses/farms were incorporated and those whose businesses/farms were not.