I’m new to CPS data so I’m wondering if ASEC data is only from the month of March? So if I am using ASEC data for each year it is from March of that year only? Or is it an annual average?
And is 2025 data just from March 2025 or is it the whole year except October?
The Current Population Survey (CPS) is a short, interrupted monthly panel survey of U.S. households. Respondent households are surveyed monthly for four consecutive months, followed by a period of eight months without surveys, and then four more consecutive months of surveys. These monthly surveys are called the Basic Monthly Survey (BMS) of the CPS, and make up the core of CPS data. Each month, a new wave of sampled respondents begins to answer surveys, so there are new respondents entering into the CPS every month. You can read more about the rotating panel design of the CPS here.
In some months, respondent households are given supplemental surveys on specific topics in addition to the BMS. The Annual Social and Economic Supplement (ASEC) is one of these supplements. The ASEC includes detailed questions about work, income, and other topics. It is fielded once a year in March to respondents who, based on the CPS rotating panel, are scheduled to complete the BMS in March. These households complete the ASEC and the BMS in March. The ASEC is also fielded to some additional respondents who are part of the “ASEC oversample” and were not in the March BMS sample that year; this happens in months other than March. The variable ASECOVERP identifies person records in the oversample. Many of the questions in the ASEC ask about the previous calendar year. You can find information about the reference period of a variable in IPUMS CPS by reading the variable description. For example, the description of OCCLY, an ASEC variable, states “OCCLY reports the person’s primary occupation during the previous calendar year.”
Linking respondents across multiple months of the CPS is possible with some limitations. You can read more about linking here. When constructing CPS panels, we recommend using either the March BMS or the ASEC from any given year. Because the ASEC includes all individuals in the March BMS from a given year as well as oversample individuals from different months of the CPS, including both the March BMS and the ASEC as part of a panel essentially results in two records from the same month for all individuals in both the BMS and the ASEC. Rather, users should choose either the March BMS or the ASEC to include as part of their panel. The ASEC includes nearly all information from the March BMS in addition to variables from the ASEC.
Note that the 2025 October BMS was not collected due to the U.S. government shutdown. All other data from 2025 are available.