Thirty years of research on general and specific abilities: Still not much more than g

Results of a 30-year research program indicate that specific cognitive abilities (s) provide little or no incremental validity beyond general cognitive ability (g). Definitions of g and s are provided and examples from training and job performance are presented. All samples are large adding to confidence in the results. On average, the increased validity for multiple regressions between using g versus g plus s was 0.02. The weight of the evidence suggests that the increment of 0.02 is an artifact of measurement error. An alternative ability model that fails to separate g and s is presented.