A statistical method for synthesizing mediation analyses using the product of coefficient approach across multiple trials
Open accessAbstract
Mediation analysis often requires larger sample sizes than main effect analysis to achieve the same statistical power. Combining results across similar trials may be the only practical option for increasing statistical power for mediation analysis in some situations. In this paper, we propose a method to estimate: 1) marginal means for mediation path a, the relation of the independent variable to the mediator; 2) marginal means for path b, the relation of the mediator to the outcome, across multiple trials; and 3) the between-trial level variance-covariance matrix based on a bivariate normal distribution. We present the statistical theory and an R computer program to combine regression coefficients from multiple trials to estimate a combined mediated effect and confidence interval under a random effects model. Values of coefficients a and b, along with their standard errors from each trial are the input for the method. This marginal likelihood based approach with Monte Carlo confidence intervals provides more accurate inference than the standard meta-analytic approach. We discuss computational issues, apply the method to two real-data examples and make recommendations for the use of the method in different settings.
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Recent methodologic developments have addressed challenging issues in causality for single and multiple randomized trials, evolving interventions, natural experiments, and multilevel as well as multidimensional situations.
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- Authors
- Huang, S., MacKinnon, D. P., Perrino, T., Gallo, C., Cruden, G., & Brown, C. H.
- Affiliations
- Vanderbilt University (US)
- Arizona State University (US)
- University of Miami (US)
- Northwestern University (US)
- Corresponding author
- Brown, C. Hendricks
- Venue
- Statistical Methods & Applications
- Published
- 2016-02-25
- Volume
- 25
- Issue
- 4
- Pages
- 565-579
- ISSN
- 1121-9130 (ISSN-L)
- 1618-2510
- 1613-981X
- PMC
- PMC5321206
- OpenAlex
- W2308692667
- Cited by
- 12
- References
- 19
- Citations by year
- 2026: 2 · 2025: 1 · 2023: 1 · 2022: 1 · 2021: 2 · 2020: 2 · 2018: 1 · 2017: 2
- FWCI
- 1.01
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- Statistical Methods & Applications (publishedVersion)
- PubMed (publishedVersion)
- PubMed Central (acceptedVersion)
- RePEc: Research Papers in Economics (submittedVersion)
- Funders
- National Institute of Mental Health (R01MH040859)
- National Institute on Drug Abuse (R01DA09757, P30DA027828, R37DA009757)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods and Bayesian Inference
- Keywords
- mediation analysis, random effects models, marginal means, statistical power
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