HI,
I'm trying to compare coefficient from different regression models with panel data.
In a normal regression I would use cross-equation test, that allows to test for the difference between two regression coefficients across independent samples. The test answers the question: “does b1 = b2?”; where b1 reflects the effect of explanatory variable within group 1 and b2 is the effect of the same variable within group 2.
code:

regr Y X1 X2 if X3 == 0

est store zero

regr Y X1 X2 if X3 == 1
est store one

suest zero one

test [zero_Y=one_Y]: X1

If I do the same thing after "xtreg, fe" (fixed effect) the output is:

Constraint 1 dropped

chi2( 0) = .
Prob > chi2 = .

Is there a way to do cross-equation test using "xtreg, fe"?
thank you