Endogenous Stratification in Randomized Experiments

© 2018 by the President and Fellows of Harvard College and the Massachusetts Institute of Technology. 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 res...

Full description

Bibliographic Details
Main Authors: Abadie, Alberto, Chingos, Matthew M, West, Martin R
Other Authors: Massachusetts Institute of Technology. Department of Economics
Format: Article
Language:English
Published: MIT Press - Journals 2021
Online Access:https://hdl.handle.net/1721.1/135812
Description
Summary:© 2018 by the President and Fellows of Harvard College and the Massachusetts Institute of Technology. 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.