The U.S. Census Bureau’s career staffers valiantly conducted the 2020 census under unprecedented challenges from the COVID-19 pandemic, but new privacy protocols meant to protect the confidentiality of participants degraded the resulting data, according to a report released Tuesday.

Key innovations such as encouraging most participants to fill out the census questionnaire online and permitting the use of administrative records from government agencies including the IRS and the Social Security Administration when households hadn’t responded allowed the statistical agency to conduct the census ''amidst an unceasing array of challenges,” an independent evaluation released by a panel of experts from the National Academies of Sciences, Engineering and Medicine said.

The once-a-decade head count determines how many congressional seats and Electoral College votes each state gets and aids in the distribution of $2.8 trillion in annual spending by the federal government.

“The overriding, signature achievement of the 2020 Census is that there was a 2020 Census at all,” the report said.

At the same time, the introduction of the new privacy method, which added intentional errors, or “noise,” to the data to protect participants’ confidentiality, was introduced late in the 2020 census planning process and wasn’t properly tested and deployed in the context of a census, according to the report.

Other concerns identified by the panel included the widening gap from 2010 to 2020 in the overcounting of non-Hispanic white and Asian residents, and the undercounting of Black and Hispanic residents and American Indians and Alaska Natives on reservations. The gap could cause the undercounted communities to miss out on their fair share of funding and political representation, the report said.

The panel also found an excess reporting of people’s ages ending in “0” or “5,” something known as “age heaping.” The growth in age heaping in 2020 was likely from census takers interviewing neighbors or landlords, if they couldn’t reach members of a household. Age heaping usually reflects an age being misreported and raises red flags about data quality.

For the 2030 census, the National Academies panel recommended that the Census Bureau try to get more households to fill out the census form for themselves and to stop relying on neighbors or landlords for household information when alternatives like administrative records are available.

The panel also urged the Census Bureau to reduce the gaps in overcounting and undercounting racial and ethnic groups.

While the National Academies panel encouraged the agency to continue using administrative records to fill in gaps of unresponsive households, it said it didn’t support moving to a records-based head count until further research was completed.

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