Comparing Models of Change to Estimate the Mediated Effect in the Pretest–Posttest Control Group Design

Matthew J. Valente, David Mackinnon

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


Models to assess mediation in the pretest–posttest control group design are understudied in the behavioral sciences even though it is the design of choice for evaluating experimental manipulations. The article provides analytical comparisons of the four most commonly used models to estimate the mediated effect in this design: analysis of covariance (ANCOVA), difference score, residualized change score, and cross-sectional model. Each of these models is fitted using a latent change score specification and a simulation study assessed bias, Type I error, power, and confidence interval coverage of the four models. All but the ANCOVA model make stringent assumptions about the stability and cross-lagged relations of the mediator and outcome that might not be plausible in real-world applications. When these assumptions do not hold, Type I error and statistical power results suggest that only the ANCOVA model has good performance. The four models are applied to an empirical example.

Original languageEnglish (US)
Pages (from-to)428-450
Number of pages23
JournalStructural Equation Modeling
Issue number3
StatePublished - May 4 2017


  • longitudinal mediation
  • mediation
  • pretest–posttest design
  • two waves

ASJC Scopus subject areas

  • General Decision Sciences
  • Modeling and Simulation
  • Sociology and Political Science
  • Economics, Econometrics and Finance(all)


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