If you conduct a placebo-controlled study, but all the participants can correctly guess which group they're in, is it really a placebo-controlled study? No, it

If you conduct a placebo-controlled study, but all the participants can correctly guess which group they're in, is it really a placebo-controlled study? No, it's not, and the question of how many allegedly double-blind studies are compromised by this leakage deserves a lot more attention.