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Annual Social and Economic Supplement Weight


ASECWT is a 10-digit numeric variable with four implied decimal places. That is, values of 0012345600 should be interpreted as 1,234.56. The IPUMS command files automatically divide ASECWT by 10,000, so no further adjustment is needed.


ASECWT is a person-level weight that should be used in analyses of individual-level CPS supplement data. Since the CPS relies on a complex stratified sampling scheme, it is essential to use one of the provided weighting variables.

Researchers should use WTFINL rather than ASECWT when they wish to conduct person-level analyses of non-ASEC data. EARNWT should be used for any analysis including a small number of person-level variables (EARNWEEK, HOURWAGE, PAIDHOUR, and UNION). Researchers should use ASECWTH for household-level analyses. ASECWTCVD is available for the 2020 ASEC to adjust for nonrandom nonresponse resulting from the COVID-19 pandemic.

User Caution: For analyses that include the 2014 ASEC sample, please see the comparability tab.

The ASEC CPS files include two groups of people who are not included in the production of published labor force statistics: (1) members of the armed services, and (2) members of the Hispanic oversample who were interviewed in months other than March. WTFINL and EARNWT assign these groups a value of 0. Both groups are assigned non-zero values in ASECWT.

ASECWT is based on the inverse probability of selection into the sample and adjustments for the following factors: failure to obtain an interview; sampling within large sample units; the known distribution of the entire population according to age, sex, and race; over-sampling Hispanic persons; to give husbands and wives the same weight; and an additional step to provide consistency with labor force estimates from the basic survey.

Estimates on the entire population are prepared by projecting forward the resident population from the last available census. These projections are derived by updating the demographic census data from a number of other data sources that account for death, births and net migration. About 3 years after every census (i.e. 2003 for the 2000 Census and 2013 for the 2010 Census), the Census Bureau updates its independent population control and provides a new weight for the relevant years.

Two important points should be noted here. First, the lag between when the Census is conducted and when the CPS weights are updated is about 3 years. While the Census data are being processed, the CPS files are made available using the weighting scheme from the US Census prior to the latest Census. Second, once the files are updated, the old weights become obsolete and are replaced in the IPUMS data extract system. Published estimates from the lag years that use the old weights are not always updated. For example, 2010 poverty estimates were released in ASEC using the 2000 population controls. Once the 2010 population controls were made available, IPUMS-CPS replaced the ASEC 2010, 2011, and 2012 weights that are based on the 2000 population control with weights that are based on the 2010 population controls. IPUMS-CPS makes available only the most up-to-date weights.


ASECWT is comparable throughout the ASEC supplements, except for 2014. Prior to 1976, the data contain a small number of valid negative values; thereafter, ASECWT has only positive values.

In the 2014 ASEC sample, the Census Bureau divided the sample randomly into a 3/8 group and a 5/8 group. The smaller portion of the sample was given the redesigned income questions. ASECWT was assigned to records so that both the 3/8ths file and the 5/8ths file independently sum to be representative of the entire US population. The flag variable HFLAG differentiates the respondent records. Please see our User Note on the 3/8 file redesign.

The most recent decennial Census has typically been used as the base population estimate, however, the 2020 Census was not suitable for this purpose due to the imposition of differential privacy meant that variables required for estimates and linking records to administrative data were unavailable and delays in both enumeration and data processing brought about by the COVID-19 pandemic. To deal with these challenges, a "Blended Base" population was established, combining information from multiple resources to arrive at the base population estimate historically provided by the decennial Census. For more information on the construction of the Blended Base for vintage 2021 estimates, see Methodology for the United States Population Estimates: Vintage 2021. The Census Bureau recommends using the 2020 Census-based weights when comparing the 2020 or 2021 ASEC to the 2022 and later ASEC data; these data are incorporated into IPUMS CPS ASECWT. The 2010 Census-based weights should be used when analyzing the 2020 or 2021 ASEC data with earlier years; these data can be downloaded from this page. See the Census Bureau's Guidance on Using Replicate Weights for more information.

Comparability with IPUMS-USA

For ASEC samples, ASECWT is fully comparable with the PERWT variable in the IPUMS census and ACS samples.


  • 1962-1967: Persons age 14+ (pre-1968 samples do not include persons under age 14).
  • 1968-2023: All persons.


Years Jan Feb ASEC Apr May Jun Jul Aug Sep Oct Nov Dec
1962 – 2023 - - X - - - - - - - - -


This variable has no flags.

Unharmonized Variables