Behavior Research Methods

, Volume 47, Issue 1, pp 85–97 | Cite as

A default Bayesian hypothesis test for mediation

  • Michèle B. Nuijten
  • Ruud Wetzels
  • Dora Matzke
  • Conor V. Dolan
  • Eric-Jan Wagenmakers
Article
First Online:

Abstract

In order to quantify the relationship between multiple variables, researchers often carry out a mediation analysis. In such an analysis, a mediator (e.g., knowledge of a healthy diet) transmits the effect from an independent variable (e.g., classroom instruction on a healthy diet) to a dependent variable (e.g., consumption of fruits and vegetables). Almost all mediation analyses in psychology use frequentist estimation and hypothesis-testing techniques. A recent exception is Yuan and MacKinnon (Psychological Methods, 14, 301–322, 2009), who outlined a Bayesian parameter estimation procedure for mediation analysis. Here we complete the Bayesian alternative to frequentist mediation analysis by specifying a default Bayesian hypothesis test based on the Jeffreys–Zellner–Siow approach. We further extend this default Bayesian test by allowing a comparison to directional or one-sided alternatives, using Markov chain Monte Carlo techniques implemented in JAGS. All Bayesian tests are implemented in the R package BayesMed (Nuijten, Wetzels, Matzke, Dolan, & Wagenmakers, 2014).

Keywords

Bayes factor Evidence Mediated effects 
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Notes

Acknowledgements

This research was supported by an ERC grant from the European Research Council. Conor V. Dolan is supported by the European Research Council (Genetics of Mental Illness; grant number: ERC–230374). Ruud Wetzels is supported by the Dutch national program COMMIT.

Supplementary material

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Copyright information

© Psychonomic Society, Inc. 2014

Authors and Affiliations

  • Michèle B. Nuijten
    • 1
  • Ruud Wetzels
    • 2
  • Dora Matzke
    • 2
  • Conor V. Dolan
    • 3
  • Eric-Jan Wagenmakers
    • 2
  1. 1.Tilburg UniversityTilburgThe Netherlands
  2. 2.Department of PsychologyUniversity of AmsterdamAmsterdamThe Netherlands
  3. 3.VU University AmsterdamAmsterdamThe Netherlands

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