Hi everyone!
This week we have *Alberto Abadie, *a Professor of Public Policy at the
Harvard Kennedy School. He will be giving a talk entitled *Endogenous
Stratification in Randomized Experiments*. The abstract for the project is
included below and available on the website (here
<http://projects.iq.harvard.edu/applied.stats.workshop-gov3009/presentations/endogenous-stratification-randomized-experiments>).
As usual, we will meet in CGIS K354 at noon and lunch will be served.
I look forward to seeing you all there! Thanks!
-- Dana Higgins
*Authors:* Alberto Abadie, Matthew M. Chingos, and Martin R. West
*Abstract:* Researchers and policy makers are often interested in
estimating how treatments or policy interventions affect the outcomes of
those most in need of help. This concern has motivated the increasingly
common practice of disaggregating experimental data by groups constructed
on the basis of an index of baseline characteristics that predicts the
values that individual outcomes would take on in the absence of the
treatment. This article shows that substantial biases may arise in practice
if the index is estimated, as is often the case, by regressing the outcome
variable on baseline characteristics for the full sample of experimental
controls. We analyze the behavior of leave-one-out and repeated split
sample estimators and show they behave well in realistic scenarios,
correcting the large bias problem of the full sample estimator. We use data
from the National JTPA Study and the Tennessee STAR experiment to
demonstrate the performance of alternative estimators and the magnitude of
their biases.
Show replies by date