[R] a question on statistics (rather than R-specific)

[Boryeu Mao]

I have used plor() to model a rather large 3-category dataset (~1500 data
points, ~15 independent variables); from the resulting model (with a
deviance slightly below the residual degrees of freedom), the training data
are placed in only the two extreme categories.  Though the result appears to
indicate that there's only a relative 'narrow' bin for the medium group,
[and when the dataset is re-organized into 2 categories, glm(family =
binomial(link = logit) ...) gives a model with a deviance reduced by about
half from the 3-category polr() result], I am questioning if this (the
'narrow-bin') interpretation is too simplistic (or entirely incorrect), and
wondering about the meaning of the absence of (fitted) data points in the
medium group.

Thanks in advance for any hints/pointers!

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