Charles Spearman originally suggested in 1927 that the varying magnitudes of the mean differences between whites and blacks in standardized scores on a variety of mental tests are directly related to the size of the tests' loadings on g, the general factor common to all complex tests of mental ability. Several independent large-scale studies…

The author refutes Humphrey's test of the Spearman hypothesis. A fair test requires that Black and White samples not be selected on any g-correlated variable, including socioeconomic status. Humphrey's factor analysis on test-score means of demographic groups, rather than on individuals, inflates g loadings and biases results. (LMO)