Redistricting to test new Census method for protecting users
WASHINGTON — Sixteen children lived alone in a wooded stretch of New York’s Jefferson County last year, at least according to the 2020 census results released earlier this month.
That’s because the Census Bureau applied a new algorithm to census results meant to protect respondents’ privacy — but it also created thousands of improbabilities like that block of “Boxcar Children” in upstate New York.
Privacy experts and the agency have argued that in the field of big data, the Census Bureau should do more to protect the privacy of respondents, hence the new algorithm, a method called differential privacy that adds statistical “noise” to data.
But some demographers fear the protections went too far. At stake is more than $1.5 trillion in federal spending over the next decade, allocated using population-based formulas. The debate over the utility of differentially private data has been theoretical — until now, as months of upcoming redistricting efforts and court fights put it to the test.
Adam Kincaid, executive director of the National Republican Redistricting Trust, said the extra noise adds another level of complexity to redistricting and related litigation.
“The differential privacy stuff injects a level of uncertainty intentionally into the data that, as Democrats bring their lawsuits and as we bring ours, will be a question that comes up time and time again,” Kincaid told reporters recently.
As states work up new maps, they’ll have to deal with improbabilities like the “Boxcar Children” blocks to draw equal population districts, despite what other records say about who actually lives there. Kincaid said his group has already identified several places where the official census results don’t match other records — particularly prisons.
On Aug. 12, the Census Bureau released highly detailed population data that local officials use for redistricting and other mapmaking purposes. But those contain fewer people than reflected in the administrative records of prisons last year, Kincaid said.
The Census Bureau first adopted differential privacy in 2019 and released several tests over the course of the past two years. The initial results contained some anomalies — graveyards populated with the living, as well as broad systemic biases that put more people in rural areas than there actually were, for example.
Earlier this year, a threejudge panel threw out a suit filed by Alabama and Rep. Robert B. Aderholt, R-Ala., which in part argued the differential privacy protections would make redistricting data unusable. The judges wrote the state would have to wait until the data’s release to prove any harm.
The Alabama Attorney General’s Office said it’s still looking at the data and may revive the suit.
Census Bureau officials have said they made improvements in the process and the data released Aug. 12 will be good enough for drawing new legislative and congressional districts. Research the agency released on Aug. 5 showed that for the smallest levels of geography — census blocks — population totals varied by less than 5%.