test str expn_stu; The test command follows the regression
( 1) str = 0.0 There are q=2 restrictions being tested
( 2) expn_stu = 0.0
F( 2, 416) = 5.43 The 5% critical value for q=2 is 3.00
Prob > F = 0.0047 Stata computes the p-value for you