In order to perform a wald test in stata, you can simply use the “test” command.
xi: reg ly lfte3 fteptaa124 fteftaa124 if count3==1 & selectie==1
test fteptaa124 = fteftaa124
* This tests whether productivity of firms’ share of part-time employees equals productivity of firms’ share of full-time employees.
* You can also look for example whether the ratio of these two variables is larger than one:
lincom fteptaa124 – fteftaa124
nlcom (ratio1: _b[fteptaa124]/_b[fteftaa124]), post
test _b[ratio1] = 1