I want to use heckman on a program evaluation of the effectiveness of
test preparation behavior on aptitude scores (afqt). Would I have to
run heckman twice; once for test-prep (YesPrep) and once for
non-test-prep (NoPrep) and then compare confidence intervals on the
constant term (afqt _cons) to determine if there were a significant
treatment effect on afqt scores? On the other hand, is there a direct
way to test for a treatment effect, such as taking the output from
heckman and running it through another procedure? Are there any good
references for this question or examples in the literature where stata
was used to test for program effectiveness.
heckman afqt iv1 iv2 iv3, select(YesPrep=iv1 iv2 iv3)
heckman afqt iv1 iv2 iv3, select(NoPrep =iv1 iv2 iv3)
Rich Riemer
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