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The Review of Economics and Statistics Vol. 100 No. 4 2018

Endogenous Stratification in Randomized Experiments

Alberto Abadie1; Matthew M. Chingos2; Martin R. West3

1 MIT · 2 Urban Institute · 3 Harvard University

open access

Abstract

Policymakers are often interested in estimating how policy interventions affect the outcomes of those most in need of help. This concern has motivated the practice of disaggregating experimental results by groups constructed on the basis of an index of baseline characteristics that predicts the values of individual outcomes without the treatment. This paper shows that substantial biases may arise in practice if the index is estimated by regressing the outcome variable on baseline characteristics for the full sample of experimental controls. We propose alternative methods that correct this bias and show that they behave well in realistic scenarios.

DOI
10.1162/rest_a_00732
Volume
100
Issue
4
Pages
567-580
Language
en
Sources
openalex crossref