Behavior Research Methods, Instruments, & Computers

, Volume 36, Issue 4, pp 717–731

SPSS and SAS procedures for estimating indirect effects in simple mediation models


DOI: 10.3758/BF03206553

Cite this article as:
Preacher, K.J. & Hayes, A.F. Behavior Research Methods, Instruments, & Computers (2004) 36: 717. doi:10.3758/BF03206553


Researchers often conduct mediation analysis in order to indirectly assess the effect of a proposed cause on some outcome through a proposed mediator. The utility of mediation analysis stems from its ability to go beyond the merely descriptive to a more functional understanding of the relationships among variables. A necessary component of mediation is a statistically and practically significant indirect effect. Although mediation hypotheses are frequently explored in psychological research, formal significance tests of indirect effects are rarely conducted. After a brief overview of mediation, we argue the importance of directly testing the significance of indirect effects and provide SPSS and SAS macros that facilitate estimation of the indirect effect with a normal theory approach and a bootstrap approach to obtaining confidence intervals, as well as the traditional approach advocated by Baron and Kenny (1986). We hope that this discussion and the macros will enhance the frequency of formal mediation tests in the psychology literature. Electronic copies of these macros may be downloaded from the Psychonomic Society’s Web archive

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© Psychonomic Society, Inc. 2004

Authors and Affiliations

  1. 1.Department of PsychologyUniversity of North CarolinaChapel Hill
  2. 2.Ohio State UniversityColumbusOhio