Monday, November 01, 2021
People, homes vanish due to 2020 census’s new privacy method
The three-bedroom colonial-style house where Jessica Stephenson has lived in Milwaukee for the past six years bustles with activity on any given weekday, filled with the chattering of children in the day care center she runs out of her home.
The U.S. Census Bureau says no one lives there.
"They should come and see it for themselves," Ms. Stephenson said.
From her majority-Black neighborhood in Wisconsin to a community of Hasidic Jews in New York's Catskill Mountains to a park outside Tampa, Fla., a method used by the Census Bureau for the first time to protect confidentiality in the 2020 census has made people and occupied homes vanish — at least on paper — when they actually exist in the real world.
It's not a magic trick but rather a new statistical method the bureau is using called differential privacy, which involves the intentional addition of errors to data to obscure the identity of any given participant.
Bureau officials say it's necessary to protect privacy in a time of increasingly sophisticated data mining, as technological innovations magnify the threat of people being "re-identified" through the use of powerful computers to match census information with other public databases. By law, census answers are supposed to be confidential.
But some city officials and demographers think it veers too far from reality — and could cause errors in the data used for drawing political districts and distributing federal funds.
At least one analysis suggests that differential privacy could penalize minority communities by undercounting areas that are racially and ethnically mixed. Harvard University researchers found that the method made it more difficult to create political districts of equal population and could result in fewer majority-minority districts.
The Census Bureau, for its part, argues that the data is every bit as good as in past censuses and that the low-level inaccuracies don't present a large-scale problem.
What's certain is that the method can produce weird, contradictory and false results at the smallest geographic levels, such as neighborhood blocks.
For example, the official 2020 census results say 54 people live in Ms. Stephenson's census block in midtown Milwaukee, but also that there are no occupied homes. In reality almost two dozen houses occupy the car-lined streets, some dating back more than a century. Forty-eight of the residents living in the block are Black, according to the census, though it's difficult to know for sure, given the whimsy of differential privacy.
In another case, the census lists no people living in the Flatwoods Conservation Park outside Tampa, even though it says there is a home occupied by people. According to Hillsborough County spokesman Todd Pratt, two county employees live there while maintaining security for the park.
And in an enclave of Hasidic Jews located in Kiamesha Lake, N.Y., 81 people are recorded as residents, but the census officially says there are no occupied homes. Sullivan County property records show almost a dozen homes whose residents have ties to the Vizhnitzer Hasidic community.
The unreliable data has created headaches for city managers and planners of small communities who worry that it may not be valid for decision-making. Eric Guthrie, a senior demographer at the Minnesota State Demographic Center, said he has been contacted by a half-dozen city managers from around the state who were concerned about potential impacts to state and federal funding.
"I explain to them there's not a method for correcting it, that it's not an error in the traditional sense," Mr. Guthrie said. "The bug is there by design."
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