"Selling mosquito nets cheaply in malaria-afflited areas is more effective than giving them away, because people who pay for them will value them more and be more likely to use them."
Plausible, but false. I got it from this New Yorker article about randomized trials of social policy, which might have other good nuggets for you as well. (The economist doing the studies annoyed some people by showing evidence that microloans don't work, or something like that--I read it in the hard copy a while ago, and the online version is behind a subscriber wall.)
This is the best I've seen in this thread. More like this please!
NB: I like not because of which turns out to be true - I doubt we're ready to take a confident position on that - but because I can easily rationalize either one as "obvious".
I'm writing the section of the rationality book dealing with hindsight bias, and I'd like to write my own, less racially charged and less America-specific, version of the Hindsight Devalues Science example - in the original, facts like "Better educated soldiers suffered more adjustment problems than less educated soldiers. (Intellectuals were less prepared for battle stresses than street-smart people.)" which is actually an inverted version of the truth, that still sounds plausible enough that people will try to explain it even though it's wrong.
I'm looking for facts that are experimentally verified and invertible, i.e., I can give five examples that are the opposite of the usual results without people catching on.
Divia (today's writing assistant) has suggested facts about marriage and facts about happiness as possible sources of examples, but neither of us can think of a good set of facts offhand and Googling didn't help me much. Five related facts would be nice, but failing that I'll just take five facts. My own brain just seems to be very bad at answering this kind of query for some reason; I literally can't think of five things I know.
(Note also that I have a general policy of keeping anything related to religion out of the rationality book - that there be no mention of it whatsoever.)