The purpose of the 2020 Post-Enumeration Survey (PES) was to measure the coverage of the 2020 Census.

The PES was designed to measure the coverage of housing units and people, excluding group quarters, people residing in group quarters, and areas of remote Alaska. It provided estimates of net coverage and components of coverage, including correct enumerations, erroneous enumerations, whole-person census imputations, and omissions. Since the PES was an evaluation, its results did not affect the 2020 Census results.

The Person Followup (PFU) operation was the fourth field operation of the PES and included PFU production and PFU Reinterview (RI). 

During the PFU operation, field staff were assigned cases in which they were required to interview knowledgeable respondents regarding people identified as requiring additional information to resolve one or more of the following: match status, person duplication, Census Day residence status, enumeration status and address information.

The data collected from PFU were used in the Person After Followup (AFU) Clerical Matching to produce the final set of match and residence status outcomes for use to develop the PES person estimates. This operation also contains valuable data for the 2030 PES planning cycle and information on the successes and shortcomings of the 2020 PES PFU operation.