Dubito Ergo Sum has a recent post that I wish I'd written. So I'll just link to it and pretend I did.
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Old Doctor Yells At Clouds
13 hours ago
First they found all the papers ever published on smoking and alzheimers, using an explicit search strategy which they describe properly in the paper – because they’re scientists, not homeopaths – to make sure that they found all of the evidence, rather than just the studies they already knew about, or the ones which flattered their preconceptions.