2 ms·
> What does that mean in practice? Imagine a hypothetical scientist that is fundamentally confused about something important, so all hypotheses they generate ar
by majormajor 3y ago
> What does that mean in practice? Imagine a hypothetical scientist that is fundamentally confused about something important, so all hypotheses they generate are false. Yet, using p=0.05, 5% of those hypotheses will be "confirmed experimentally". In that case, it is not 5% of the "experimentally confirmed" hypotheses that are wrong -- it is full 100%. Even without any cherry-picking.
Well, that's example is also introducing dependence, which is a tricky thing of course whenever we talk about chance and stats.
But there's also another issue - a statement like "5% of positive published results are by chance since we have a p<=0.05 standard" treats every set of results as if p=0.05, whereas some of them are considerably lower anyway. Though the point of bad actors cherry-picking to screw up the data also comes into play here.
(And of course, fully independent things in life are much harder to find than one might think at first.)
- stkdump 3y agoI agree that the point about the 'confused scientist' is important, even if that itself is not stated clearly enough. Here is my own reading: Imagine that a scientist is making experiments of the form: Does observable variable A correlate with observable variable B? Now imagine that there are billions of observable variables and almost all of them are not correlated. And imagine that there is no better way to come up with plausible correlations to test than randomly picking variables. Then it will take a very long time and a very large number of experiments to find a pair that is truly correlated. It will be inevitable that most positive results are bogus.