Coverage Error Optimal Confidence Intervals
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We propose a framework for ranking confidence interval estimators in terms of their uniform coverage accuracy. The key ingredient is the (existence and) quantification of the error in coverage of competing confidence intervals, uniformly over some empirically-relevant class of data generating processes. The framework employs the "check" function to quantify coverage error loss, which allows researchers to incorporate their preference in terms of over- and under-coverage, where confidence intervals attaining the best-possible uniform coverage error are minimax optimal. We demonstrate the usefulness of our framework with three distinct applications. First, we establish novel uniformly valid Edgeworth expansions for nonparametric local polynomial regression, offering some technical results that may be of independent interest, and use them to characterize the coverage error of and rank confidence interval estimators for the regression function and its derivatives. As a second application we consider inference in least squares linear regression under potential misspecification, ranking interval estimators utilizing uniformly valid expansions already established in the literature. Third, we study heteroskedasticity-autocorrelation robust inference to showcase how our framework can unify existing conclusions. Several other potential applications are mentioned.
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