Hi,
I ran the Qic test with around 30 variables and the parameter p was equal to zero. p is the number of parameters in the model, so it cannot be equal to zero. What would be the explanation? How to correct the problem?

Code:
xi: qic dependent_var i.var1 var2...var30, i(id) t(year) family (nbinomial) link(log) corr(exchangeable) robust eform
This results in the following output:

Code:
              QIC and QIC_u
___________________________________________
Corr =         exchangeable
Family =          nbinomial
Link =                  log
p =                       0
Trace =              35.257
QIC =             72647.876
QIC_u =           72577.362
___________________________________________
Thank you.