An unexpected gem from last year's Journal of the American Psychoanalytic Association:
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Surprisingly, it has nothing to do with psychoanalysis. Rutherford and colleagues performed a meta-analysis of lots of clinical trials of antidepressants. Neuroskeptic readers will be all too familiar with these. But they did an interesting thing with the data: they compared the benefits of antidepressants in trials with a placebo condition, vs. trials with no placebo arm, such as trials comparing one drug to another drug.
Why do that comparison? Because the placebo effect is likely to be stronger in trials with no placebo condition. If you volunteer for a placebo controlled trial, you'll know that you've got (say) a 50-50 chance of getting inactive sugar pills. You'll probably be uncertain whether or not you'll get better, maybe even quite worried. On the other hand if you're in a trial where you definitely will ...
