- Speaker: Caleb Miles (Columbia University)
- Discussant [standard form]: James Robins (Harvard University) and Thomas Richardson (University of Washington)
- Title: Two fundamental problems in causal mediation analysis
- Abstract: Scientists are often interested in understanding mediating mechanisms that can help explain causal effects. A vast body of literature on mediation analysis has accumulated since two foundational articles (Robins and Greenland, 1992; Pearl, 2001) formalized mediation in the language of causality. However, causal mediation analysis poses many fundamental, interesting, and unresolved difficulties in its causal interpretation, nonparametric identification assumptions (which are much stronger than most typical causal assumptions), and statistical inference. I will discuss some of my work in two of these categories: (i) the interpretation of alternative estimands that have been proposed to circumvent the standard identification assumptions, and (ii) the implicit assumptions embedded in the standard mediation identification assumptions and their shortcomings in handling the inherent time-varying nature of mediators.