Table 2 Overview of the analytic process using a Rasch model approach
Steps | Psychometric property | Measuring | Statistical approach |
|---|---|---|---|
1 | Rating scale functioning | Does the rating scale function consistently across items? | |
2 | Internal scale validity | How well do the actual item responses match the expected responses from the Rasch model? | Item goodness-of-fit statistics |
3 | Internal scale validity | Is the scale unidimensional? | Principal component analysis |
4 | Person-response validity | How well do the actual individual responses match the expected responses from the Rasch model? | Person goodness-of-fit statistics |
5 | Person-separation reliability | Can the scale distinguish at least two distinct levels of sense of coherence in the sample tested? | Person-separation index |
6 | Internal consistency | Are item responses consistent with each other? | Cronbach’s alpha coefficient |
7 | Differential item functioning (DIF) | Are item difficulty calibrations stable in relation to demographic and clinical variables? | Mantel-Haenszel statistics |