ABSTRACT
This chapter describes mediation analysis for the multiple mediator model, which was a straightforward extension of methods to investigate the single mediator model. The multiple mediator model described first includes two mediators that come between the independent variable and the dependent variable. Examples of multiple mediator models are described and the equations for the two mediator model are given along with formulas for standard errors of effects in the model. The causal steps method to assess mediation for one mediator also applies in multiple mediator models with a few limitations. A total effect may be statistically significant yet one or more mediated effects may be inconsistent. The estimate of the mediated effect and its standard error can be used to construct confidence limits for symmetric intervals and asymmetric intervals. M. J. Harris and R. Rosenthal conducted a meta-analysis of 135 studies of the mediators of the relation between teacher expectancy and student achievement.
