A Distribution-Free Approach to Longitudinal Mediation Analysis with Count Outcomes and Mediators

• Activity Number: 329
• Type: Topic Contributed
• Date/Time: Tuesday, August 5, 2014 : 10:30 AM to 12:20 PM
• Sponsor: Mental Health Statistics Section
• Author(s): Douglas Gunzler*+
• Companies: Case Western Reserve University
• Keywords: mediation analysis ; functional response models ; structural equation model ; weighted generalized estimating equations II ; missing data ; overdispersion

Abstract

In this talk, we extend a new, robust approach to address the limitations of current structural equation models (SEM) within the context of longitudinal mediation analysis for outcomes and mediators in the form of a count or rate, when data is overdispersed, by utilizing a class of functional response models (FRM). Being distribution-free, the FRM-based approach does not impose any parametric assumption on data distributions. In addition, by extending inverse probability weighted estimates to the current context, the FRM-based SEM provides valid inference for longitudinal mediation analysis under the two most popular missing data mechanisms; missing completely at random (MCAR) and missing at random (MAR). We illustrate the approach with both real and simulated data.