Loo comparison in reference to standard error

[avehtari]

@jonah

There’s no “correct” number of standard errors to look for. I think I’ve even seen @avehtari recommend as many as 5SE somewhere!

Aki, is that your general recommendation now?

The problem is that the current SE estimate is optimistic, and the theory say that it in the worst case the true SE can be even twice the estimate, so based on that 4SE using the current estimate is safe. We are working on better SE estimate, but it will take some time to test that it really works.