Mediation: R package for causal mediation analysis

In this paper,we describe the r package mediation for conducting causal mediation analysis in applied empirical research. in many scientific disciplines,the goal of researchers is not only estimating causal effects of a treatment but also understanding the process in which the treatment causally affects the outcome. causal mediation analysis is frequently used to assess potential causal mechanisms. the mediation package implements a comprehensive suite of statistical tools for conducting such an analysis. the package is organized into two distinct approaches. using the model-based approach,researchers can estimate causal mediation effects and conduct sensitivity analysis under the standard research design. furthermore,the design-based approach provides several analysis tools that are applicable under different experimental designs. this approach requires weaker assumptions than the model-based approach. we also implement a statistical method for dealing with multiple (causally dependent) mediators,which are often encountered in practice. finally,the package also offers a methodology for assessing causal mediation in the presence of treatment noncompliance,a common problem in randomized trials. © 2014,journal of statistical software. all rights reserved.