Posted by
Ryan on
Apr 04, 2013; 10:32pm
URL: http://spssx-discussion.165.s1.nabble.com/Repeated-measures-analysis-of-fractions-summing-to-a-constant-tp5719257p5719271.html
Would the OP mind explaining exactly what the DV is? It might help shed light on how to proceed, notwithstanding other interesting solutions. Speaking of which, the idea of converting the probs to logits is intriguing. I am generally in favor of the logit scale because of its properties, but the fact that it addresses the linear dependence is an added bonus here.
Anyway, I would appreciate if the OP would be willing to tell us more about the DV.
Ryan
On Apr 4, 2013, at 4:05 AM, Kirill Orlov <
[hidden email]> wrote:
> Consider you have a between-within design: several between-subject groups and several (3 or more) repeated measures (= within-subject) trials. It's all very classic and typical. The nuance, however, is that the values for every subject sum across the repeated levels to a **constant**. This is because the data are complementary, i.e. percentages of fractions, so, in this case they sum to 100 for every individual. For example, with 3 RM levels, a respondent's data is like 30%, 22%, 48% (sum=100); for another respondent 25%, 33%, 42% (sum=100).
>
> I know that I can analyze between-groups X repeated-measures count data via Generalized Estimating Equations procedure. By I doubt in this case because the values *sum to a constant*, they are complementary fractions; they are not counts of successes in repeated independent trials!
>
> Can I analyze such data in SPSS and how? Thanks.
>
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