Model 2 reveals the relation between item properties and disengagement.
Model 2 provided insights into the relation between item properties and disengagement.
Although the results have been satisfactory, CTT has not considered item properties and person characteristics in the model.
In the current research, the PCM was used to report item properties and rating scale structure of the KIDSCREEN-27.
According to the generally satisfactory item properties and good item validity coefficients regarding HbA1c the overall item selection appears very satisfying.
In pre-testing the questionnaire had already been found to possess convincing item properties and feasibility and encouraging indications of validity.
The additional analyses of the subsamples revealed slightly better item properties and consistency in type 1 patients which can be partly attributed to the difference in sample size.
Modern methods, like Item Response Theory (IRT), quantitatively assess item properties and identify items with the highest information content [ 3, 4], enabling development of more precise instruments [ 4, 5].
The results obtained in terms of number of items, properties of cross-section measurement and relationship with sociodemographic and clinical variables will be further assessed in the prospective validation study (second phase of the project).
IRT quantitatively establishes item-measurement properties and identifies items with the highest information content.
To assess item characteristics and the measurement model (scaling) for the measure, the following tests were performed: For item reduction, both item psychometric properties and conceptual importance were taken into consideration in making retention/deletion decisions for the initial item pool.
