Why randomize? Job-training program and wages
A city reports that residents who enrolled in a voluntary job-training program earn more a year later than those who did not enroll, and cites this as proof the program raises wages.
Explain why the earnings gap cannot establish that the program raises wages, and design an evaluation that can. Why is randomization essential?
Your answer
This one is open-ended. Work it through, then check your reasoning against the full solution.