Optimal Debiased Inference on Privatized Data via Indirect Estimation and Parametric Bootstrap

TL;DR

This paper introduces a debiased inference framework for privatized data using indirect estimation and bootstrap, improving the accuracy of confidence intervals and hypothesis tests.

Contribution

It proposes a novel adaptive indirect inference method with theoretical guarantees, addressing biases in private data inference.

Findings

Produces confidence intervals with proper coverage

Maintains correct type I error rates in hypothesis testing

Achieves minimum asymptotic variance among consistent estimators

Abstract

We design a debiased parametric bootstrap framework for statistical inference from differentially private data. Existing usage of the parametric bootstrap on privatized data ignored or avoided handling possible biases introduced by the privacy mechanism, such as by clamping, a technique employed by the majority of privacy mechanisms. Ignoring these biases leads to under-coverage of confidence intervals and miscalibrated type I errors of hypothesis tests, due to the inconsistency of parameter estimates based on the privatized data. We propose using the indirect inference method to estimate the parameter values consistently, and we use the improved estimator in parametric bootstrap for inference. To implement the indirect estimator, we present a novel simulation-based, adaptive approach along with the theory that establishes the consistency of the corresponding parametric bootstrap estimates, confidence intervals, and hypothesis tests. In particular, we prove that our adaptive indirect estimator achieves the minimum asymptotic variance among all ``well-behaved'' consistent estimators based on the released summary statistic. Our simulation studies show that our framework produces confidence intervals with well-calibrated coverage and performs hypothesis testing with the correct type I error, giving state-of-the-art performance for inference in several settings.