Practice of causal inference with the propensity of being zero or one: assessing the effect of arbitrary cutoffs of propensity scores.

ABSTRACT: Causal inference methodologies have been developed for the past decade to estimate the unconfounded effect of an exposure under several key assumptions. These assumptions include, but are not limited to, the stable unit treatment value assumption, the strong ignorability of treatment assignment assumption, and the assumption that propensity scores be bounded away from zero and one (the positivity assumption). Of these assumptions, the first two have received much attention in the literature. Yet the positivity assumption has been recently discussed in only a few papers. Propensity scores of zero or one are indicative of deterministic exposure so that causal effects cannot be defined for these subjects. Therefore, these subjects need to be removed because no comparable comparison groups can

SUBMITTER: Kang J 

PROVIDER: S-EPMC6714558 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature