  A recent paper in Sci. Adv. by Miller et al. concludes that GREs do not help
predict whether physics grad students will get Ph.D.s. The paper makes numerous
elementary statistics errors, including introduction of unnecessary
collider-like stratification bias, variance inflation by collinearity and range
restriction, omission of needed data (some subsequently provided), a peculiar
choice of null hypothesis on subgroups, blurring the distinction between
failure to reject a null and accepting a null, and an extraordinary procedure
for radically inflating confidence intervals in a figure. Release of results of
simpler models, e.g. without unnecessary stratification, would fix some key
problems. The paper exhibits exactly the sort of research techniques which we
should be teaching students to avoid.
