To determine the factor structure underlying the PDD items, we computed five CFA models (see Figure 1). We examined parameter estimates and indices of global model fit, including the Comparative Fit Index (CFI), Tucker-Lewis Index (TLI), and the Root Mean Square Error of Approximation (RMSEA) (Hu and Bentler 1999) to identify the best-fitting models. The Mplus DIFFTEST procedure was used to test for significant differences in fit among nested models.
