Accordingly, we allow for items with different numbers of response categories, as well as varying distances across response categories (e.g., Gibbons et al., 2007).
The pain and function subscales of the KOOS and SF-36 measures hold different number of items, and the different items may have different numbers of response options.
Lastly, we wanted to study the effects of different numbers of response options on neural activity, whether choosing the response according to a rule or not.
It allows items to have different numbers of response categories [ 29], and does not assume the distance between response thresholds is uniform for all items [ 34].
The data were analyzed with a non-parametric statistical method, suitable for comparison of scales with different numbers of response alternatives.
Interchangeability between scales with different numbers of response categories requires a high level of order-consistency, i.e. lack of overlapping of the records on one scale relative the other.
Six of these twelve measures had items with different numbers of response categories (American Knee Society Score, Lequesne Hip and Knee Indices, Hospital for Special Surgery Knee Score, Harris Hip Score, SF-36 & the Arthritis Impact Measurement Scale with between 1 and 6 response categories depending on the measure and item).
In the RSM, the response categories are defined identically for all items, whereas they are allowed to differ in the PCM (e.g., items with different number of response categories and/or different labels).
However, it is possible for items to have different number of response categories on a questionnaire.
The GRM is suitable for ordered polytomous responses and can deal with items that have a different number of response categories.
