At first glance this seems like a horribly flawed study. It seems misleading to call this a placebo effect when it is clearly the result of selection bias. The

At first glance this seems like a horribly flawed study. It seems misleading to call this a placebo effect when it is clearly the result of selection bias. The paper makes it clear that this is intentional, but I'm not sure they've really shown anything novel here, just demonstrated what should already be well known. I.e., badly designed studies may contain bias.