“Statistical Notes § Inferring Mean IQs From SMPY/TIP Elite Samples”, Gwern2014-07-17 (, , ; similar)⁠:

Miscellaneous statistical stuff

Samples taken from the extremes of mixtures of distributions can have very different properties than random samples, such as the tail effect of wildly disproportionate representation of one distribution due to order statistics/threshold selection.

This can be used to infer differing means.

I demonstrate working backwards from the racial composition of SMPY/TIP samples of extremely (1-in-10,000) gifted youth to estimate the overall racial means, which is consistent with the known racial means and hence an unbiased selection process, using ABC to infer Bayesian credible intervals on the estimated means.