The next talk in our CTML Seminar Series is coming up on February 19th! Join us for an engaging discussion led by Dr. Kara Rudolph on "Improving Efficiency in Transporting Average Treatment Effects." This talk will take place at 12:00PM at Berkeley Way West, 5th Floor, Room 5401.
We develop flexible, semiparametric estimators of the average treatment effect (ATE) transported to a new population (``target population'') that offer potential efficiency gains. First, we propose two one-step semiparametric estimators that incorporate knowledge of which covariates are effect modifiers and which are both effect modifiers and differentially distributed between the source and target populations. These estimators can be used even when not all covariates are observed in the target population; one requires that only effect modifiers are observed, and the other requires that only those modifiers that are also differentially distributed are observed. Second, we propose a collaborative one-step estimator when researchers do not have knowledge about which covariates are effect modifiers and which differ in distribution between the populations, but require all covariates to be measured in the target population. We use simulation to compare finite sample performance across our proposed estimators and existing estimators of the transported ATE, including in the presence of practical violations of the positivity assumption. Lastly, we apply our proposed estimators to a large-scale housing trial.