Following individuals

Does SERIAL (identifies household) and PERNUM (identifies person in household) stay consistent across samples? I’d like to be able to follow the time series change of individuals.

The sample definitions say that a combination of SAMPLE, SERIAL, and PERNUM uniquely identifies a person but that would only work if SERIAL and PERNUM stay consistent correct? And I’m looking for a time series so SAMPLE would definitely change, but would the last 2 digits stay the same, since the first 4 identify the year?

IPUMS USA cannot be linked longitudinally, if that’s what you’re saying, though there are some linkages possible in early censuses (pre 1940) and, on a limited basis, in the CPS.

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The data provided by IPUMS USA come from samples of the U.S. decennial census and American Community Survey. These samples are called the public use microdata samples (PUMS) and are subsets of the data collected by the Census Bureau. These samples are intended to be used as repeated cross-sections, and can generally not be used as a panel. There is a low likelihood that the same individuals are included in adjacent years or more than one sample and, even if they were, there is no way to identify them in the PUMS.

SERIAL and PERNUM are sample-specific identifiers that you can use to uniquely identify individuals (SERIAL and PERNUM) or households (just PERNUM) within a given sample. They cannot be used to link people over time.

There are some options for linking older U.S. census data, such as the multigenerational longitudinal panel (MLP) project, which is available with the public use version of full count historical census data. We also offer licenses to access restricted use versions of historical full count census data, which includes individual respondents’ names. Users can create their own links based on names and other variables. If you are interested in access to the restricted full count data, please send us an email at

If you are interested in panel data, you may want to check out IPUMS CPS. The Current Population Survey (CPS) is a short panel survey of U.S. households that includes some similar information to the census and ACS, with a focus on work-related variables. We also offer data from the Medical Expenditure Panel Survey (MEPS) on IPUMS MEPS. MEPS is a panel survey focused on health care utilization, health, and wellbeing.

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