Dear OP,
I applaud your effort to promote clear thinking on effects of policy. One thing I wanted to mention is that even programs with weak effects may be eventually worthwhile if there is some cancellation of direct effects of the program by some indirect effects. Even if not worthwhile directly, interventions with "effect cancellation" may perhaps be informative for designing future interventions. People in "mediation analysis" worry about these things a lot.
Analyzing mediation is tricky because it needs strong assumptions.
A piece I saw that Benjamin Todd adapted from THINK's module on charity assessment. Some of you may recall the network's recent launch.
cipergoth said that it should be emphasised that this isn't a trick question where the answer is they all worked or none did.
I thought Round 2 would have no effect and expected Round #5 to have no effect not a negative one, I got 6 out of 8 correct. How well did you do?
I recommend checking out the links and references. Gwern's comment there was also interesting.