I want to check if my instrument variable is a weak instrument, in order to do so I have to perform an F test.
Here I have ran the regression with xi: xtivreg wage race age married (education = parents education), fe first


My problem is that I want to have the estat firststage, to check if the instrument is weak. This is not possible with xtivreg, this estat firststage I can only get with using
xi: ivregress 2sls wage race age married (education = parents education)

Now the problem is that the coefficients for xi: ivregress 2sls and xi: xtivreg is different. I can conclude for the estat firststage that the instrument is not weak.
But how can I else test if the instrument is weak or not for the xtivreg , I have to stick with the xtivreg model.