Computing internal consistency for ordinal variables in JASP
Together with two other researchers, I am analyzing the internal consistency of a newly developed self-esteem scale, that exists of 3 questions in the short version and 5 questions in the long version. Question answers are rank ordered, so the questions are of the ordinal measurement level. I used the McDonald's omega to compute the internal consistency of the questions, but I am starting to wonder if this is the best procedure? Is there any other internal consistency I could compute in JASP (or maybe another software), that might be better suitable for our set of questions?
We also have low levels of the McDonald's omega, about .310, which is lower than we hoped for. Of course, this could have something to do with the low number of questions, with the questions not measuring a unidimensional concept or with limited understanding of the questions by respondents (although we consider the last two options not that likely). Has any of you ever struggled with unexpected low levels of internal consistency? What was the reason for that?
Thank you in advance for your response! It is greatly appreciated!