Differentially Private Medians and Interior Points for Non-Pathological Data

Maryam Aliakbarpour, Rose Silver, Thomas Steinke, Jonathan R. Ullman

Abstract: We construct differentially private estimators with low sample complexity that estimate the median of an arbitrary distribution over $\mathbb{R}$ satisfying very mild moment conditions. Our result stands in contrast to the surprising negative result of Bun et al. (FOCS 2015) that showed there is no differentially private estimator with any finite sample complexity that returns any non-trivial approximation to the median of an arbitrary distribution.