st: nbreg with cluster gives NO LR test

["Sanz De Galdeano, Anna" <Anna.Sanz.De.Galdeano@IUE.it>]

Dear Statalist members,
 
Could anyone explain me why when using nbreg with the cluster option, I get no LR test (the test for alpha=0 that instead appears by default when no cluster option is included). I am using stata 8.2. Amd I doing somthing wrong?
 
Many thanks and best regards
Anna

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