Fig. 2.

Timeline of several key mediation methods developed over the years. Orange color represents initial methods with rudimentary ideas for mediation analysis. Green color represents classical mediation methods developed for univariate and multivariate mediation analysis. Yellow color represents high-dimensional mediation methods targeted for a large number of potential mediators. HIMA: high-dimensional mediation analysis, BAMA: Bayesian mediation method, DACT: divide-aggregate composite-null test. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)