GRE (Graduate Record Examination)

The GRE is the weakest predictor of graduate success on this list, with a mere 0.15 correlation to PhD completion—so weak that over 100 programs have dropped it as a requirement. It systematically disadvantages women, who score an average of 50 points lower on quantitative sections than men with identical GPAs, and penalizes test-taking anxiety among minorities. This flimsy measurement outperforms only the Gaokao in irrelevance to actual ability, yet still sways funding and admissions. Concrete data: 0.15 correlation with PhD completion; 50-point quantitative gap between women and men with matched GPAs.