By showing that -logit- with two and -ologit-
with three give essentially equivalent results?
Nick
[email protected]
E. Michael Foster
> I have data on an ordered outcome coded from 1 to 3.
> Suppose I suspect
> that the distinction between levels 2 and 3 is
> meaningless--i.e., nothing
> substantive would be lost if I just recoded the 3s to 2s.
>
> One implication would be that the proportional odds
> assumption
> wouldn't not hold for the 3-category model because the
> difference between
> levels 2 and 3 has nothing to do with the X variables.
>
> I could test this, but it seems like a weak test. The
> proportional odds assumption could be violated for any of
> several reasons.
>
> How do I demonstrate to my psychologist colleagues (the
> measure is a psych
> measure) that collapsing 3 categories into 2 is harmless?
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