In all, 16 items were removed from the scale according to the criteria of item selection; 10 of them were true-or-false questions, which showed poor discriminative power and small factor loading.
Table 5 shows that the first criterion of item internal consistency was met for three scales, since the Pearson, Spearman and polychoric correlations took values above 0.40.
Concerning the EFA in Study 1, our statistical consultant set the criterion of item retention at a factor loading of.32 or higher, which is generally accepted as the minimum value for an item loading on a given factor [ 65].
Our two validity checklists are helpful but do have limitations, as some items are optional and there is no weighting criteria of individual items.
Besides meeting criteria I and II, patients meeting any 2 criteria of the items III, IV, VI, and VII are defined as clinical diagnosed.
Guidelines for inclusion/exclusion criteria of individual items of data were provided to ensure data consistency between centres, with the research team answering specific queries.
Measurement precision In four of the fifteen examples, the standard error became ≤ 0.32 for each dimension before the CAT stopped at the stop criterion of twenty items (twice after item 9, once after item 15, and once after item 16).
In total 330 three- or four- item combinations were possible, and 51 (15%) combinations met the criteria of containing item 9 and representing three domains.
We have not been able to identify any alienation scales tested according to these more demanding criteria of modern item response theory.
The psychometric criteria of this item were proved to be good.
