Following the recommendations in Peters,21 we used exploratory factor analysis (EFA) in the development sample to determine the scale’s dimensionality based on the polychoric correlation matrix of the scales’ items.40 The factor structure in the development sample was then confirmed through confirmatory factor analysis (CFA) in the validation sample. Adequacy of fit was evaluated using the Root Mean Square Error of Approximation (RMSEA) and the Comparative Fit Index (CFI). We used minimum rank factor analysis to estimate the percentage of common variance explained by the EFA and CFA models,41,42 and parallel analysis43 and the Bayesian Information Criterion (BIC) for factor retention. Closeness to unidimensionality was assessed using the Explained Common Variance (ECV).44
