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Group Differences in Cognitive Ability: Evidence of a Jensen Effect

Harrison Kane


Historically, tests of intelligence and cognitive ability have revealed significant differences between races, with Blacks performing significantly below all other groups. The provenance of these differences has sparked considerable debate among psychologists, educators, sociologists, and policymakers. The present study investigates one possible explanation for these observed race differences, namely Spearman’s g. Using a large representative standardization sample from the USA, significant White-Black differences in cognitive ability were identified across all tests. Using the method of correlated vectors, these differences were found to correlate significantly with estimates of psychometric general intelligence (Spearman's g) obtained from each group. Thus, there is support for a "Jensen Effect".

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