Internal consistency was good for the four scales: appropriateness (alpha = 0.85), management support (alpha = 0.81), efficacy (alpha = 0.70) and personal valence (alpha = 0.66) (Table 2).
The research team also evaluated the value of each sub-scale and appropriateness of each item in the scale for 3- to 6-year-olds in Hong Kong.
The objectives of the cognitive debriefing interviews were to understand the question-and-answer process used by the caregiver, refine question wording, optimize the response scales, confirm appropriateness of the recall period, and confirm the content validity of the instrument.
The interviews were structured to evaluate the caregiver question/answer process, assess comprehension and refine question wording, optimize the response scales, confirm appropriateness of the recall period, confirm the content validity of the items, and confirm there were no missing concepts.
On inspection of Table 4, it is evident that Cronbach's alpha coefficients were high for the first two scales, acceptable for the "service appropriateness" scale and low for the multi-item scale that relates to service planning.
This refers to how well each item fits within the proposed scale and the appropriateness of the scaling assumptions.
Denser distributions toward the right of the scale indicate greater appropriateness.
Although the scale considers the appropriateness of the randomization method, which is fundamental, it does not include concealment.
Note that item 20 in the "service appropriateness" scale had in fact a high factor loading also with the one-item factor mentioned above.
Modern test theory with Rasch analysis provides additional and more detailed psychometric information regarding the dimensionality of the scale, validity and appropriateness of summated scores, response categories, targeting of the scale, and item bias, i.e. differential item functioning (DIF).
