Bureau of Economic Analysis

Their demonstration is a brewery: five aggregated statistics about beer-related businesses form a solvable system of equations that recovers individual firms' employee counts, even after careful rounding. Coarsening, they argue, loses usefulness AND fails at privacy — the worst of both.

The thread added context and doubt. A Stanford CS voice noted 2020 was the first census to use differential privacy, that lawsuits question its constitutionality, and that citizenship status could be inferred by cross-referencing products. A practitioner just sighed that an interesting technology had gone political.

Damien Desfontaines walks through a trade with no good side: strip the noise and the only privacy tools left are coarsening and suppression, which gut accuracy for small and minority populations while still leaving the data attackable.

Reconstruction attacks, he notes, are just solving a system of equations, and removing the noise makes that trivial. A privacy-company founder complicates the villain story: the 2020 rollout, he says, was a genuine internal disaster.