Department of Electrical Engineering
Stanford, CA 94305
Institutional Affiliation: Stanford University
NBER Working Papers and Publications
|October 2018||Matrix Completion Methods for Causal Panel Data Models|
with Susan Athey, Mohsen Bayati, Nikolay Doudchenko, Guido Imbens: w25132
In this paper we study methods for estimating causal effects in settings with panel data, where a subset of units are exposed to a treatment during a subset of periods, and the goal is estimating counterfactual (untreated) outcomes for the treated unit/period combinations. We develop a class of matrix completion estimators that uses the observed elements of the matrix of control outcomes corresponding to untreated unit/periods to predict the “missing” elements of the matrix, corresponding to treated units/periods. The approach estimates a matrix that well-approximates the original (incomplete) matrix, but has lower complexity according to the nuclear norm for matrices. From a technical perspective, we generalize results from the matrix completion literature by allowing the patterns of m...