Codes and Frequencies
METRO reports whether the household was located inside or outside a Metropolitan Statistical Area (MSA). Households inside an MSA are further classified by whether they were located in the central city of the MSA. Households outside an MSA are further classified by farm or nonfarm status.
Information on whether the household was located within an MSA was added by the National Center for Health Statistics, not collected from respondents.
In the original NHIS public use files, for 1982 forward, information about whether a non-MSA household was classified as "Nonfarm" or "Farm" was included in the same variable that reported location inside or outside a central city for MSA households. Prior to 1982, these two pieces of information were in two different variables in the original public use files. In IPUMS NHIS, for years prior to 1982, the information was all included in a single variable via supplemental programming to increase comparability over time.
The "NCHS Definitions" section of the National Center for Health Statistics website provides the following information about classifications for place of residence for the survey:
The NCHS Definitions webpage further notes that "the largest city in an MSA is always a central city." Households coded as "MSA, not in Central City" are located in any part of an MSA that is not part of the central city itself. Households coded as "Not in MSA" are in all other places in the country except MSA's.
Only households in areas that were classified as "rural" were at risk of being classified as farms. For 1969-1981, a rural household was classified as a farm if: 1) it was located on 10+ acres that yielded $50+ from the sale of crops, livestock, and other farm products; or, 2) it was located on less than 10 acres that yielded $250+ from the sale of crops, livestock, and other farm products. Beginning in 1982, a farm was any rural household that yielded $1,000+ from the sale of crops, livestock, and other farm products. These definitions of a farm basically matched those adopted in the 1960 and 1970 censuses and in the 1980-2000 censuses, respectively. Survey respondents supplied the information whether the size of the place that the household owned or rented was 10 or more acres (for 1969-1981) and about whether the sale of farm products during the past 12 months reached a specified threshold ($50, $250, or $1000).
Non-interview households are those in which the dwelling was unoccupied or in which the residents were either absent or refused to participate in the survey.
This variable is largely comparable over time.
As noted in the description of this variable, the definition of metropolitan population prior to 1995 was based on the OMB's 1983 definition using the 1980 census; the definition of metropolitan population for 1995 forward was based on the OMB's 1993 definition using the 1990 census. As also noted, the criteria for "farm" status changed in 1982.
- 1963-1996: All households.
- 1963, 1966-1967, 1969-1996 : HHWEIGHT