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Adaptive Principal Component Regression with Applications to Panel Data
Anish Agarwal · Keegan Harris · Justin Whitehouse · Steven Wu

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in “Could it have been different?” Counterfactuals in Minds and Machines »

Principal component regression (PCR) is a popular technique for fixed-design error-in-variables regression, a generalization of the linear regression setting in which the observed covariates are corrupted with random noise. We provide the first time-uniform finite sample guarantees for online (regularized) PCR whenever data is collected adaptively. Since the proof techniques for PCR in the fixed design setting do not readily extend to the online setting, our results rely on adapting tools from modern martingale concentration to the error-in-variables setting. As an application of our bounds, we provide a framework for counterfactual estimation of unit-specific treatment effects in panel data settings when interventions are assigned adaptively. Our framework may be thought of as a generalization of the synthetic interventions framework where data is collected via an adaptive intervention assignment policy.

Author Information

Anish Agarwal (Amazon)
Keegan Harris (Carnegie Mellon University)
Justin Whitehouse (Computer Science Department, Carnegie Mellon University)
Steven Wu (Carnegie Mellon University)

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