st: nonsense category in ordered logit

["E. Michael Foster" <foster@pop.psu.edu>]

Hi,
	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?

thanks,
Michael Foster
Professor of Health Policy and of Demography

   
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