The design of the CPS is described in Chapter 4 of this report. To summarize, the CPS, sponsored jointly by the Bureau of Labor Statistics and the Census Bureau, is a national household sample survey. Like most major national surveys, the CPS covers the civilian noninstitutionalized household population, including noninstitutionalized groups not living in conventional housing units and groups living in housing containing nine or more persons unrelated to the person in charge. Its design is a nationally and state-level representative sample, but estimates for small states have large confidence intervals. It has a very large sample size of 60,000 households (about 119,000 individual respondents in households, with about 31,000 under age 18) interviewed every month. In addition to its core content, a different supplement is fielded each month. The CPS has high response rates, and adding the FSS to it is relatively inexpensive and allows for timely production of annual prevalence data on food insecurity. Data are available from the Census Bureau within 3–4 months and released by USDA in published form to the public about a year after collection. The cost of the supplement to USDA is about $450,000 each year. This includes data collection, initial editing for confidentiality and weighting, incorporating household-level food security variables calculated from the initial data by USDA, preparation of documentation for the public use file, and purveying the public use data on CD-ROM and on the Census Bureau’s Data FERRET system.2
As noted earlier, CPS uses a rotating sample design and technically is a panel survey because a household is in the survey for four months, then out for eight months, and then back in for four months. The sample unit is the household address and not the household, and for the reinterview period the original occupants of the address may have moved since the earlier interviews. One person is interviewed to obtain information for the entire household. The CPS is in the field every month, but only the Annual Social and Economic Supplement to the CPS in March and some rotation groups in February and April include detailed information on household income. The FSS is administered in December, at which time very little income information is collected. The CPS does not collect information on general health of the population or nutritional intake.