Analyses were conducted using R version 2.10.1 (21). Open Mx version 1.0.6 (22) was used for the factor analysis. Missing data was handled using full information maximum likelihood. Model fit was evaluated using χ2 tests and the difference in the Akaike Information Criterion (23) between the saturated and alternative models (positive values indicate the alternative provides better fit), separately for the four samples under study. We also report the root mean squared error of approximation, where values of .06 or less indicate a very good fit (24). The χ2 test provides an exact test of model fit, but is sensitive to sample size and the magnitude of correlations among measures, and is always significant (p<.05) when statistical power is high (e.g., in large samples). It is often significant even when the model provides an accurate and useful representation of the data (25). As such, other fit indices have been developed and are primarily used to evaluate model fit. The root mean square error of approximation attempts to correct deficiencies of the χ2 by adjusting for the degrees of freedom and
