R help - Feb 2011 - Ordinal logistic regression (lrm)- checking model assumptions

Dear all,

I have been using the lrm function in R to run an ordinal logistic  
regression and I am a bit confused about the methods for checking the  
model assumptions.

I have produced residual plots in R of the score.binary type which I  
think look ok. However, the partial type plots show bell shaped  
patterns and have crossing lines, indicating violation of parallelism.  
However, I noticed on the help page that for ordinal models,  
simulations where proportional odds are satisfied have also produced  
similar patterns.

I have also run the regression in SPSS and found that the test of  
parallel lines shows that the assumption of parallelism has not been  
violated. However, I have read that this is not a reliable method.

I am finding it very confusing to determine if my model meets the  
necessary assumptions. Does anybody know the best way to do this?

Any advice would be much appreciated,

Thank you,

Anna