Isaiah Andrews

Department of Economics, E52-504
77 Massachusetts Avenue
Cambridge MA 02139

E-Mail: EmailAddress: hidden: you can email any NBER-related person as first underscore last at nber dot org
NBER Program Affiliations: LS
NBER Affiliation: Faculty Research Fellow

NBER Working Papers and Publications

September 2017Weighting for External Validity
with Emily Oster: w23826
External validity is a fundamental challenge in treatment effect estimation. Even when researchers credibly identify average treatment effects – for example through randomized experiments – the results may not extrapolate to the population of interest for a given policy question. If the population and sample differ only in the distribution of observed variables this problem has a well-known solution: reweight the sample to match the population. In many cases, however, the population and sample differ along dimensions unobserved by the researcher. We provide a tractable framework for thinking about external validity in such cases. Our approach relies on the fact that when the sample is drawn from the same support as the population of interest there exist weights which, if known, would allow...
March 2017Identification of and Correction for Publication Bias
with Maximilian Kasy: w23298
Some empirical results are more likely to be published than others. Such selective publication leads to biased estimators and distorted inference. This paper proposes two approaches for identifying the conditional probability of publication as a function of a study's results, the first based on systematic replication studies and the second based on meta-studies. For known conditional publication probabilities, we propose median-unbiased estimators and associated confidence sets that correct for selective publication. We apply our methods to recent large-scale replication studies in experimental economics and psychology, and to meta-studies of the effects of minimum wages and de-worming programs.
November 2014Measuring the Sensitivity of Parameter Estimates to Estimation Moments
with Matthew Gentzkow, Jesse M. Shapiro: w20673
We propose a local measure of the relationship between parameter estimates and the moments of the data they depend on. Our measure can be computed at negligible cost even for complex structural models. We argue that reporting this measure can increase the transparency of structural estimates, making it easier for readers to predict the way violations of identifying assumptions would affect the results. When the key assumptions are orthogonality between error terms and excluded instruments, we show that our measure provides a natural extension of the omitted variables bias formula for nonlinear models. We illustrate with applications to published articles in several fields of economics.

Published: Isaiah Andrews & Matthew Gentzkow & Jesse M. Shapiro, 2017. "Measuring the Sensitivity of Parameter Estimates to Estimation Moments*," The Quarterly Journal of Economics, vol 132(4), pages 1553-1592.

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