Re: [Gretl-users] tsls tests
On Wed, 21 Apr 2010, Allin Cottrell wrote:
On Wed, 21 Apr 2010, Summers, Peter wrote:
> I'm still not sure about the df in the Hausman test though. In
> the last model it seems to me that this should be 2, not 1...
I will take another look at that.
You still have perfect collinearity in the relevant respect. The
issue is that in the Verbeek schooling dataset the experience
values are "fake" (as is quite often the case in labor-market
datasets); they are calculated numbers representing "potential
experience", as in
exp76 = age76 - ed76 - 6
This means that when you run the unrestricted regression for the
Hausman test one of the "hat"-variables gets dropped
automatically, leaving just one degree of freedom for the test.
Allin