Data processing is currently in the spotlight with the US Census Bureau director’s recent announcement that routine “processing anomalies” will likely delay delivering state counts to the president well after the December 31 deadline. This delay caused the data processing period to be cut short by 60 days and has raised concerns about quality.

Counting the entire US population is a messy endeavor. People make mistakes filling out the census—sometimes predictably and other times not—resulting in questions being left blank or filled out inconsistently. Such errors would be flagged and resolved during the data processing period, often with protocols developed in advance.

Yet, the pandemic has made this anything but a typical census. The declaration of a COVID-19 national emergency happened simultaneously with the start of census fieldwork, delaying various elements of census operations. People relocating to new residences put the accuracy of the address-based enumeration of the census at risk. Though we have scant information from the Census Bureau about the nature of these processing anomalies, warning signs in recent months point to some clues.

The Census Bureau has been especially concerned about the enumeration of college students during the pandemic and produced materials to clarify that those living in off-campus housing or dormitories should be counted there. The Census Bureau enlisted additional help from universities to improve the accuracy of the count, but had mixed success getting cooperation.

The pandemic affected the count in other ways. Staffing and field operations became more logistically challenging, stymying efforts to reach hard-to-count populations. Scheduling delays meant enumeration was concurrent with wildfires in the West and hurricane season in the Gulf, adding to the uncertainty. These examples underscore how anomalous 2020 was for conducting the census.

Read the full article about census data processing by Diana Elliott at Urban Institute.