As the factorial analysis of both the first validation and replication phases revealed a predominant factor that could be split into four underlying dimensions, it was decided to construct a unidimensional form of the questionnaire, that could produce an overall global outcome that could be very useful in case of evaluation study.
Both in the adolescent and the adult sample and both in Wave 1 and Wave 2, the items formed unidimensional scales, with a minimum explained variance of 88%.
Lastly, the unidimensionality of POES needs to be tested to ensure that the sum of items forms a unidimensional scale, as this is a basic prerequisite for combining any set of items into a total score.
We assumed that the 28-item EORTC QLQ-C30 fits Rasch model's specification and forms a unidimensional construct.
In this study we assumed that the 28-item EORTC QLQ-C30 fits Rasch model's specification and forms a unidimensional construct.
The Italian version formed a unidimensional, probabilistic Guttman-like scale explaining 41%% of the variance.
Rasch analysis of the OENAT revealed that the seven domains of the OENAT formed a unidimensional scale, suggesting the use of domain scores rather than individual item scores.
To explore whether the items form one unidimensional scale, or several dimensionally distinct subscales, we used an automated item selection procedure (AISP) [52, Chap. 5, pp. 65 - 90].
The Rasch analysis also showed that the items in the original or modified FACIT-F did not form a unidimensional structure.
The seven communication items of the GP Patient Survey have high reliability (Cronbach's alpha = 0.99), which strongly suggests that they form a unidimensional scale [ 27].
Previous Rasch modeling of the PF-10 indicated that the items form a unidimensional, hierarchical continuum with stable item difficulty estimates across diverse patient groups [ 24, 30].
