Counterpoint: Mediation Formulas With Binary Mediators and Outcomes and the Rare Outcome Assumption

摘要

In their accompanying article, Samoilenko and Lefebvre ( . 2019;188(7):1203–1205) correctly note 2 typographical errors in the formulas presented in a 2011 paper on placental abruption by Ananth and VanderWeele ( . 2011;174(1):99–108). Fortunately, to the best of our knowledge, researchers are using our methods papers and Dr. VanderWeele’s 2015 book on mediation analysis ( ; Oxford University Press, New York, New York), rather than the paper on placental abruption, to carry out their direct and indirect effect analyses; and in our methods papers and the book, the formulas are correct. The formulas discussed by Samoilenko and Lefebvre and in our work make reference to a “rare outcome assumption.” In evaluating this assumption, it is important to note that the outcome is to be relatively rare —a point that is often neglected.