... But this kind of complexity is everywhere we look, including in campaigns. Will “Issue A” or “Issue B” cause more people to vote for the Republican or Democratic candidate? We can ask voters with survey research. But we know people are bad at self-prediction, and often treat that kind of question as a chance to express preexisting support or opposition to the candidate. In fact, asking voters what’s an effective message will often make a bad message look good, or a good one look bad.
This is exactly the challenge many in the pro-life movement have faced. How do we know whether, and with whom, a pro-life electoral message works?
The solution , as I see it, is to randomly assign voters to receive either one of the political messages or a placebo — just like in our imaginary protest vs bar-hopping example. Read more here.