Estimating and Comparing Specific Mediation Effects in Complex Latent Variable Models

This teaching note starts with a demonstration of a straightforward procedure using M plus Version 6 to produce a bias-corrected (BC) bootstrap confidence interval for testing a specific mediation effect in a complex latent variable model. The procedure is extended to constructing a BC bootstrap confidence interval for the difference between two specific mediation effects. The extended procedure not only tells whether the strengths of any direct and mediation effects or any two specific mediation effects in a latent variable model are significantly different but also provides an estimate and a confidence interval for the difference. However, the M plus procedures do not allow the estimation of a BC bootstrap confidence interval for the difference between two standardized mediation effects. This teaching note thus demonstrates the LISREL procedures for constructing BC confidence intervals for specific standardized mediation effects and for comparing two standardized mediation effects. Finally, procedures combining M plus and PRELIS are demonstrated for constructing BC bootstrap confidence intervals for the difference between the between-part and within-part path coefficients in multilevel models and for examining models with interactions of latent variables.