st: prtab

["daniela ferrante" <danielaferrante@hotmail.com>]

Dear Stata users,

I've got three variables: v12 v3 v6 that are categorical and each of them is 
classified in five categories.
I'd like to apply a multinomial logistic regression to predict the value of 
v12 given a value of v3 and v6.

I use:

mlogit v12 v3 v6
prtab v3 v6

I really can't understand the use of prtab. There are some cell that are 
blank but prtab gives a probability.
Does someone know something more about prtab and if mlogit is correct?

Thank very much

Daniela

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