Stata coding question - Running wald test of equality after simultaneous equations framework (using -cmp-)

[Courtney Bass]

Hi Statalisters,

I am using the -cmp- command to run a simultaneous equations model. I'd like to test (within each equation) whether certain explanatory variables have equivalent coefficients. There are only two equations in my cmp framework, but each of the equations have a similar list of explanatory variables. Thus, I want to test whether var1 = var2 within equation 1 (where dependent variable = DV#1) and I'd also like to test whether var1 = var2 within equation 2 (where dependent variable = DV#2). Any thoughts?

I tried using the following command after the cmp model:

test var1 = var2

The result that I got displayed the below, as well as the corresponding chi(2) and p-value associated with the Wald test:

[DV#1]var1 - [DV#1]var2 = 0


My questions are:
1. Is it safe to assume that the result I've gotten does, in fact, test whether var1 and var2 are equal within equation 1.
2. How can I tell Stata to test the same variables, but using equation 2?

I've consulted the Stata help file, but it doesn't provide an example for the syntax to use when testing the equivalence of coefficients after multi-equation estimation commands...

Thanks,
Courtney

[Courtney Bass]

I believe the following syntax does the trick, and allows me to test the equivalence of the coefficients of var1 and var2 within model 2, for anyone interested:

[DV#2]var1 = [DV#2]var2

[Clyde Schechter]

Thank you for closing the thread and sharing your solution.

[Maryam Bidgoli]

Hi Courtney,

I am using the -cmp- command to run a simultaneous equations model. Two dependent variables are endogenous (heath and labor supply). I'd like to test exogeneity of health in the labor supply equation. I was wondering if you could help me how to conduct a Wald test of exogeneity after _cmp_ command.

Many thanks,
Maryam