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Related Concept Videos

One-Way ANOVA: Unequal Sample Sizes01:15

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Permutation-based methods for mediation analysis in studies with small sample sizes.

Miranda E Kroehl1, Sharon Lutz2, Brandie D Wagner1

  • 1Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.

Peerj
|February 1, 2020
PubMed
Summary
This summary is machine-generated.

For small sample mediation analysis, the Permutation Supremum test under Reduced Models (PSRM) maintains accurate error rates, unlike other permutation tests. This method is recommended for reliable indirect effect evaluation in limited data scenarios.

Keywords:
Intersection union testMediation analysisPermutation under full modelPermutation under reduced modelProduct of coefficients test

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Area of Science:

  • Statistics
  • Biostatistics
  • Epidemiology

Background:

  • Mediation analysis assesses exposure effects on outcomes via intermediate variables (mediators).
  • Permutation testing is valuable for evaluating indirect effects in small sample sizes, maintaining type I error rates.
  • Existing permutation methods for small sample mediation analysis have limitations when covariates are included.

Purpose of the Study:

  • To evaluate two novel permutation approaches for testing indirect effects in mediation analysis with covariates.
  • To compare these new methods against the standard permutation approach for small sample sizes.

Main Methods:

  • Simulation studies were conducted to assess type I error rates and statistical power.
  • Two new methods, Indirect Effect under Reduced Models (IERM) and Permutation Supremum test under Reduced Models (PSRM), were evaluated.
  • The performance was compared to the Indirect Effect under Full Models (IEFM) approach.

Main Results:

  • The PSRM approach effectively controlled type I error rates across all simulated conditions.
  • The IERM approach demonstrated inflated type I error rates in many scenarios.
  • The standard IEFM approach showed inflated type I error rates under specific conditions, while power was comparable between PSRM and IEFM.

Conclusions:

  • The PSRM approach is recommended for mediation analysis in small sample studies.
  • PSRM offers a reliable method for assessing indirect effects when covariates are present.
  • The findings suggest PSRM is a superior alternative to existing methods like IEFM for small sample mediation analysis.