Adjusting treatment effect estimates by post-stratification in randomized experiments

Adjusting Treatment Effect Estimates by Post-Stratification in Randomized Experiments∗

Experimenters often use post-stratification to adjust estimates. Post-stratification is akin to blocking, except that the number of treated units in each stratum is a random variable because stratification occurs after treatment assignment. We analyze both post-stratification and blocking under the Neyman-Rubin model and compare the efficiency of these designs. We derive the variances for a pos...

Adjusting treatment effect estimates by postâ•’stratification in randomized experiments

Experimenters often use post-stratification to adjust estimates. Post-stratification is akin to blocking, except that the number of treated units in each stratum is a random variable because stratification occurs after treatment assignment. We analyse both post-stratification and blocking under the Neyman–Rubin model and compare the efficiency of these designs. We derive the variances for a pos...

Lasso adjustments of treatment effect estimates in randomized experiments.

We provide a principled way for investigators to analyze randomized experiments when the number of covariates is large. Investigators often use linear multivariate regression to analyze randomized experiments instead of simply reporting the difference of means between treatment and control groups. Their aim is to reduce the variance of the estimated treatment effect by adjusting for covariates....

Optimal Stratification in Randomized Experiments

This paper shows that stratifying on the conditional expectation of the outcome given baseline variables is optimal in matched-pair randomized experiments. The assignment minimizes the variance of the post-treatment difference in mean outcomes between treatment and controls. Optimal pairing depends only on predicted values of outcomes for experimental units, where the predicted values are the c...

Online Appendix: Optimal Stratification in Randomized Experiments