Effects of Sample Size, Estimation Methods, and Model Specification on Structural Equation Modeling Fit Indexes

A Monte Carlo simulation study was conducted to investigate the effects on structural equation modeling (SEM) fit indexes of sample size, estimation method, and model specification. Based on a balanced experimental design, samples were generated from a prespecified population covariance matrix and fitted to structural equation models with different degrees of model misspecification. Ten SEM fit indexes were studied. Two primary conclusions were suggested: (a) some fit indexes appear to be noncomparable in terms of the information they provide about model fit for misspecified models and (b) estimation method strongly influenced almost all the fit indexes examined, especially for misspecified models. These 2 issues do not seem to have drawn enough attention from SEM practitioners. Future research should study not only different models vis-à-vis model complexity, but a wider range of model specification conditions, including correctly specified models and models specified incorrectly to varying degrees. © 1999, Lawrence Erlbaum Associates, Inc.