R for SAS and SPSS Users by MUENCHEN, R. A.

Abstract

Is there increasing cognitive partitioning by occupation over time? Herrnstein and Murray's The Bell Curve strongly suggests such a trend. Herrnstein and Murray specify 12 occupations as “high-IQ professions.” They argue that as jobs in these occupations increase over time, more people with high IQs are drawn to these occupations. Thus, there is a growing concentration of the cognitive elite in high-IQ occupations and increasing cognitive partitioning by occupation. However, I find Herrnstein and Murray's analysis problematic due to lack of evidence and misinterpretation of data. Using data from the National Longitudinal Survey of Youth and the Wisconsin Longitudinal Survey, I rank occupations by incumbents' mean IQ and demonstrate that Herrnstein and Murray overestimate the rankings of some high-IQ occupations, the mean IQ level of persons in high-IQ occupations, and the percentage of high-IQ persons engaged in high-IQ occupations. In addition, using data from the General Social Survey, 1974–1998, I find no evidence that cognitive partitioning by occupation has increased over time. Author Keywords: the Bell Curve; cognitive ability; IQ; occupation; social stratification