Doubly-robust estimators within the one-step and TMLE frameworks could exhibit finite-sample bias and excess variability under positivity violations. We comment on how the application of a stabilization factor may improve the efficiency property of one-step estimator and TMLE, and the comparisons with their collaborative counterparts using the adaptive propensity scores.
"Comment: Stabilizing the Doubly-Robust Estimators of the Average Treatment Effect under Positivity Violations." Statist. Sci. 35 (3) 503 - 510, August 2020. https://doi.org/10.1214/20-STS774