CPSIDP is a 14-digit numeric variable.

Description

CPSIDP is an IPUMS CPS defined variable that uniquely identifies individuals across CPS samples. The first six digits of CPSIDP index the four-digit year and two-digit month that the household was first in the CPS. CPSIDP allows users to link a respondent appearing with a designated household roster line number (LINENO) across samples, based on the 4-8-4 rotation pattern, by assigning a unique CPSIDP value to this line number. CPSIDP will only ever appear for a maximum of 8 times, which is the number of times a household may be observed in the CPS survey (as indexed by MISH). In some cases, individuals will appear fewer than 8 times due to migration, mortality, non-response, and recording errors. Extensive documentation about the creation of CPSIDP is available elsewhere.

Users should note that it is important to verify CPSIDP linkages with AGE, SEX, and RACE. In some cases CPSIDP will result in erroneous links, which are due to errors in the source data. Cases with the same CPSIDP value may also have inconsistent responses across samples due to errors on the part of the respondent or in recording the response. Ultimately, it is up to the individual researcher to determine the acceptability of the linkages made using CPSIDP.

CPSIDP may also be used to link ASEC respondents who are in the March Basic Monthly file to other months of CPS data. This linking is made possible by IPUMS through the creation of MARBASECIDP.

To get started using CPSIDP, users may want to sort their data file by CPSIDP and MISH to create a person-time file.

Users should take care when including the March Basic or ASEC as part of their linking. Respondents who are part of the ASEC oversample (as indicated by ASECOVERP) have a CPSIDP value of 0. For further information about the relationship between the March Basic and the ASEC, please see our additional documentation.

Comparability

Linking between 1976 and 1977 is limited. It is possible to link using CPSIDP within 1976 and from 1976 supplement files to 1977 basic files but not from 1976 basic files to 1977 files; nor is linking between supplement and basic files in 1977 possible. For more details about CPSIDP creation in the 1976-1988 period, see Flood et al., 2020. For more details about CPSIDP from 1989 forward, see Drew et al., 2014.

Universe

Flags

Unharmonized Variables