Due to issues with the nonresponse bias present in the American Community Survey (ACS) data collected in 2020, the 2016–2020 ACS 5-year housing unit weighting was modified to enhance our ability to mitigate that bias. Our revised methodology incorporated the entropy-balance weighting (EBW) methodology used to produce the 2020 ACS 1-year experimental data products into our standard production methodology. The goal was to leverage the EBW to reduce the bias in the 2020 portion of the 5-year data while keeping our standard methodology as intact as possible to support producing estimates for all of our standard 5-year geographic areas.

To accomplish this integration, we devised a modified set of steps in the estimation methodology to partially process the four years of data from 2016–2019 using our standard methods before combining those data with the 2020 data that had been processed using the EBW methodology. Once the years 2016–2020 were pooled together, we applied population and housing unit control totals, derived from estimates produced by the Population Estimates Program, as we normally do.

This modification will be applied to subsequent 5-year estimates that include data collected in 2020.

For additional details, view the 2016–2020 ACS 5-year Accuracy of the Data document and Modifications to the Entropy Balance Weighting for the 2016-2020 ACS 5-Year Release.