Psychometric analysis of the systemizing quotient (SQ) scale

The psychometric properties of the systemizing quotient (SQ) developed by Baron‐Cohen (2003) are investigated in three studies. Furthermore, we examine the notion that the ability to systemize should be independent of intelligence. In Studies 1 and 2, confirmatory factor analyses are used to examine the factor structure of the SQ. Study 3 examines the relationship between systemizing, mental rotation and intelligence. Studies 1 and 2 indicate that the SQ does not possess a unifactorial structure but is best considered as four related factors; Study 3 found that SQ was not related to intelligence, although mental rotation was. A four factor structure using fewer items was a better fit for the data than either the original version of the SQ or Wakabayashi et al.'s (2006) revised version. Overall these results support Baron‐Cohen's view that SQ is not related to intelligence. Although mental rotation is correlated to SQ, it is not the main determinant of SQ. The problems of self‐report measures are discussed along with the difficulties related to measuring systemizing.