Internal Census Emails Show Bureau Concern Over Data Fuzzing

The U.S. Census Bureau expert in charge of providing redistricting data to states raised alarm that a new privacy-protecting process could hurt small towns and make data too inaccurate for redrawing district maps, internal emails show.

The emails are attached to a brief filed by the Alabama attorney general in a lawsuit challenging the Census Bureau’s new “differential privacy” techniques. Those methods are meant to thwart sophisticated data miners by planting mathematical noise into the information that the bureau distributes to the states. That information is used to redraw congressional, statehouse, and local government district maps.

“The data must reflect ...