Imai, Kosuke, Luke Keele, Dustin Tingley, and Teppei Yamamoto. (2014). ``Comment on Pearl: Practical Implications of Theoretical Results for Causal Mediation Analysis.'' Psychological Methods, Vol. 19, No. 4 (December), 482-487.



Mediation analysis has been extensively applied in psychological and other social science research. Recently, a number of methodologists have developed a formal theoretical framework for mediation analysis from a modern causal inference perspective. In Imai et al. (2010), we have offered one such approach to causal mediation analysis that formalizes identification, estimation, and sensitivity analysis in a single framework. This approach has been used by a number of substantive researchers and in subsequent work we have also further extended it to more complex settings and developed new research designs. In an insightful article, Pearl (2013) proposes an alternative approach that are based on a set of assumptions weaker than ours. In this commentary, we demonstrate that the theoretical differences between our identification assumptions and his alternative conditions are likely to be of little practical relevance in the substantive research settings faced by most psychologists and other social scientists. We also show that our proposed estimation algorithms can be easily applied in the situations discussed in Pearl (2013). The methods discussed in this commentary and many more are implemented via open-source software mediation (Tingley et al., 2013).

  Other information

The project page for the statistical analysis of causal mechanism: Webpage.

© Kosuke Imai
 Last modified: Thu Jan 22 22:23:24 EST 2015