st: prvalue and the invisible prediction

["Robert Bozick" <robertbozick@hotmail.com>]

Hey Listers --

I want STATA to estimate predicted probabilities for my binary outcome for 
different levels of my independent variables.  I am estimating a logit 
model.  STATA estimates the model without any error messages.  I then use 
the prvalue commands to obtain the predicted probabilities.  To be specific, 
the code I use is:

prvalue, x(hourw10=1 hourw20=0 hourw30=0 hourw40=0 hourw40p=0 offcampus=1 
apt=0 fam=0 misres=0 off20=0 off30=0 off40=0 apt10=0 apt20=0 apt30=0 apt40=0 
apt40p=0 fam10=0 fam20=0 fam30=0 fam40=0 fam40p=0 misr30=0 misr40=0 
misr40p=0)

Again, I receive no error messages, but STATA does not produce the predicted 
probabilities (or they are invisible).  The output looks like this:

logit: Predictions for persist

 Pr(y=continuo|x):        .   95% ci: (     .,     .)
 Pr(y=no_persi|x):        .   95% ci: (     .,     .)

The predictions are not there!  Help!  Does anyone know what I am doing 
wrong?  Why can I not get STATA to produce the predicted values?

Thanks in advance,
Robert

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