nulldata 50
set seed 3379985
genr x1 = uniform()
genr x2 = uniform()
genr u = normal()
genr x3 = 2*x1 + 3*x2 + u
genr e = normal()
genr y = 100+2*x1+3*x2+.1*x3 + 2*e
ols y const x1 x2 x3
omit x1 x2 x3