Abstract
R2 effect-size measures are presented to assess variance accounted for in mediation models. The measures offer a means to evaluate both component paths and the overall mediated effect in mediation models. Statistical simulation results indicate acceptable bias across varying parameter and sample-size combinations. The measures are applied to a real-world example using data from a team-based health promotion program to improve the nutrition and exercise habits of firefighters. SAS and SPSS computer code are also provided for researchers to compute the measures in their own data.
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This research was supported by the National Institute on Drug Abuse Grant DA09757. A portion of this article was presented at the 2005 Annual Meeting of the American Psychological Association in Washington, DC.
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Fairchild, A.J., MacKinnon, D.P., Taborga, M.P. et al. R2 effect-size measures for mediation analysis. Behavior Research Methods 41, 486–498 (2009). https://doi.org/10.3758/BRM.41.2.486
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DOI: https://doi.org/10.3758/BRM.41.2.486