http://spssx-discussion.165.s1.nabble.com/Question-Regarding-Analysis-tp5737799p5737825.html
> Hi Brian. Re treating the sum of the eight items as interval, here's an
> interesting (and provocative) article I was alerted to just yesterday:
>
> Liddell TM, Kruschke JK. Analyzing ordinal data with metric models: What
> could possibly go wrong?. Journal of Experimental Social Psychology. 2018
> Nov 1;79:328-48.
>
>
https://osf.io/9h3et/download?format=pdf>
> If you have institutional access to sciencedirect.com, you can get the
> final
> published article here:
>
>
https://www.sciencedirect.com/science/article/pii/S0022103117307746>
> From p. 344 in the final published article:
>
> "Some authors have argued that, despite the ordinal character of
> individual
> Likert items, averaged ordinal items can have an emergent property of an
> interval scale and so it is appropriate to apply metric methods to the
> averaged values (e.g., Carifio and Perla, 2007, Carifio and Perla, 2008.
> It
> is intuitively plausible that the averaging could produce data that at
> least
> look more continuous and therefore may not suffer from the problems
> pointed
> out above. Unfortunately that intuition is wrong. We show in this section
> that an average of ordinal items has the same problems as a single item."
>
> HTH.
>
>
> bdates wrote
>> I have been asked to analyze data from a large (n=402) study of an
>> intervention for adolescents. One of the measures, that is quite highly
>> used, is the CAFAS, which assesses functioning in children and youth, age
>> 6 to 18. There are eight items, scored from 0 to 30 in increments of 10
>> (i.e., 0, 10, 20, 30). The eight items produce a total score ranging from
>> 0 to 240. A review of the literature does not reveal really good
>> reliability, either alpha, or ICC (the measure is clinician-completed).
>> Item-total correlations range from .20 to .57. The distribution of scores
>> on all items is skewed, either positively or negatively. I'm proposing to
>> analyze each of the scales as if they were ordinal and the total score as
>> interval, using a repeated measures approach since there are multiple
>> measures per youth. I neither designed the study nor chose the measures.
>> I've simply been commissioned to analyze the data. Any thoughts on
>> treating the items as ordinal? I know it's conservative, but I have
>> difficulty with a four-point discontinuous scale as really interval in
>> nature.
>>
>>
>> Brian
>>
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>
> -----
> --
> Bruce Weaver
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