Abstract:

Integrating moderation and mediation models has been a popular topic of study in social science methodology. A moderated mediation model is a combination of both moderation and mediation models. When a mediation effect is moderated by a moderator, the effect is termed moderated mediation and the model is a moderated mediation model. There are three common types of moderated mediation models: first-stage moderated mediation, second-stage moderated mediation, and dual-stage moderated mediation. Three methods of testing moderated mediation models are based on the Bootstrap asymmetric confidence interval and the Bayesian asymmetric credible interval. These methods include a subgroup approach, difference approach, and products of coefficients approach. The products of coefficients approach is recommended to analyze first-stage or second-stage moderated mediation models. The difference approach is recommended to analyze dual-stage moderated mediation models. A simulation study found that the Bayesian credible interval without informative prior yielded higher power than the Bootstrap percentile confidence interval, and comparable power to the Bootstrap bias-corrected confidence interval. In the present study, we used an example to illustrate how to conduct the proposed procedure by using MPLUS and WinBUGS software. MPLUS and WinBUGS programs are provided in the appendix to facilitate the implementation of the Bootstrap method to analyze moderated mediation effects. The programs can be managed easily by empirical researchers. To explore the present situation and problems of using three moderated mediation analysis methods in psychological researches in China, this article reviewed 12 studies published in Chinese psychological journals, retrieved from the CNKI database, since 2009 to 2014.

Key words: Moderated mediation, Bootstrap, Bayesian, difference approach, products of coefficients approach