st: Hausman test

[Carmen Blanco <blnco.mc@gmail.com>]

Dear statalist,

I have some problem with Hausman test. When I compare between random
effects and fixed effects with Hausman test, Stata reports me this:

                  chi2(4) = (b-B)'[(V_b-V_B)^(-1)](b-B)
                          =   -45.27    chi2<0 ==> model fitted on these
                                        data fails to meet the asymptotic
                                        assumptions of the Hausman test;
                                        see suest for a generalized test

Could someone tell me, please, how to solve this problem in order to
know if my model is random or fixed effects?

Thanks

C.B.
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