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by nextos 913 days ago
Bayesian statistics, the way Andrew Gelman practices it, comes naturally when you are interested in generative models of data. You can still use maximum likelihood estimates, but these become fragile when you have hierarchical / multilevel models.

Multilevel models are fantastic to address a problem that is often ignored by frequentist approaches, the need for shrinkage and information sharing. This pops up all the time in modern statistics. For example, if you test 1000 hypotheses, calculating p-values and adjusting these with some multiplicity correction scheme is not sufficient.

You should borrow information across random variables with a multilevel model to avoid estimating exaggerated effects in tests whose outcome is deemed to be significant. Andrew Gelman's post is concerned with this topic.

Another point is that Gelman et al. use weakly informative hyperpriors. These are not really subjective. If anything, they usually regularize solutions by pushing effects towards zero. Plus, on multilevel models, priors are only needed on hyperparameters.

1 comments

I use mixed level models for longitudinal analysis pretty regularly. There the point has been to account for correlated dependent observations (e.g. repeated variables within a participant.

However it seems that you are suggesting another use. If I have 10 cognitive measures each measured once in my subjectd, the default has been to do a multiple comparison correction, either FDR or FWER on 10 tests. We know that the 10 tests are not truly independent, so Bonferroni is probably too conservative.

It seems here you suggest running this with test being a random effect. I've seen this approach with item level data in a task, but I didn't really think to do it when the tests are not from the same battery, construct. And more to the point, this fixed effect model would be of no particular interest, while random effect CIs are difficult to estimate. So I am left a bit confused.