Selected items were next fit to a Rasch model. This model was chosen rather than more complex, multi-parameter IRT models for consistency with Jellinek’s theory, which focused on developmental sequence and not the relative discriminability of each stage. However, to ensure a linear dimension, items that did not fit the model were excluded based on the OUTFIT statistic (Linacre, 2005). The severity parameters for the Rasch model are given for each item in Table 1, with higher values signifying items indicative of more severe problems. The correspondence between empirical and theoretical representations of the severity of the various indicators was assessed by computing the rank-order correlation between the order hypothesized by Jellinek and the observed empirical ordering of items. This coefficient (rho = .39) suggested moderate correspondence.
