In order to perform a wald test in stata, you can simply use the “test” command.

* regression:

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

One variation of this commend that I find most useful is “testparm”. “testparm” allows you to give variable lists for two types of tests, joint significance (Ho: all coefficients are equal to zero, Ha: at least one is different from zero) and joint equality with the option ëqual” (Ho: all coefficients are equal to each other, Ha: at least one is different from the rest). These commands are easily combined with global and local macros, and it also works with multiple equation commands such as “sureg” or “reg3”.

Ex:

*

global varlist var1 var2 var3

sureg ($varlist = varx vary varz)

for var $varlist: testparm var*, equation(X)

for var $varlist: testparm var*, equal equation(X)

*