The General Factor in Spearman's Theory of Intelligence

Abstract

SPEARMAN'S theory may be summarised as follows: (1) A mathematical theorem, that when all the tetrad differences such as (r_abr_cd-r_acr_bd) formed from N variables a, b, c, d, . . . vanish, each variable may be considered as the sum of two parts (or ‘factors’) which are numerical multiples of a general factor g (the same for every variable) and of a specific factor s (different in each case). These N + 1 factors are all uncorrelated with each other. (2) The attribution principally to mere error of sampling of the non-vanishing of the small tetrad differences formed from dissimilar mental measurements. (3) The interpretation of g as general mental energy, and of each s as a specific ability.