Properties of a Sensitivity Analysis for Causal Mediation and Path Analysis

Music City Center 

Causal path analysis, an extension of causal mediation analysis, seeks to decompose a treatment or exposure effect into multiple path-specific effects. One particular methodology, generalized causal mediation and path analysis, allows for discrete or continuous mediators (and final outcome) and handles path models with multiple causally-ordered sets of mediator. As this method, which uses an extended mediation-formula for estimation, makes strong sequential ignorability assumptions, it is important to accompany analyses with relevant sensitivity analyses. The present work presents and explores a flexible approach to sensitivity analysis, based on a regression relationship between potential outcomes for pairs of model variables with possible unmeasured confounding. We provide simulation study results showing good properties for path-specific effect estimates under the extended (sensitivity analysis) model, and expound on the interpretation of the sensitivity parameter. Using our recently developed GMediation R package, we illustrate the new methods using data from a study of causal pathways between socioeconomic status and adolescent dental caries.

causal inference

generalized linear models

path-specific effects

sequential ignorability 

Biometrics Section