Fallacious analyses cannot test for racial differences: A reply to Gorey and Cryns

Although insufficient information was provided to allow an examination of the actual calculations in Gorey and Crynsʹ meta-analysis, their results and conclusions are demonstrably false. For example, they erroneously reported the point-biserial effect size r of the white-black difference in IQ alternately as 0.226 and 0.022, even though it is known that the actual value is 0.50 (100 − 85/15 = z score of 1.00 which transforms to the point-biserial r of 0.50). Gorey and Crynsʹ analysis also failed to detect widely acknowledged black-white differences in out-of-wedlock births, crime, and numerous other indicators of ‘social organization’. Much of this failure to detect reality was due to inclusion of ‘matched samples’ at distributional extremes. Regardless, their conclusions do not follow from their analyses. First, their only statistically significant results were consistent with those reported by Rushton (Personality and Individual Differences, 9, 1009–1024, 1988). Second, their ‘per cent variance accounted for’ argument is statistically correct but substantively erroneous. Finally, Gorey and Cryns excluded from discussion macrophysiological variables like testosterone, rate of two-egg twinning, and brain size (which, like IQ, also shows a black-white r = 0.50). The racial gradient on all these variables is found worldwide and is directly relevant to causal analysis.