spearman

Spearman is an English surname historically associated with the occupation of a spear bearer. It is most commonly linked to Charles Edward Spearman, a British psychologist and statistician whose work helped shape modern psychometrics and statistics.

Charles Spearman (1863–1945) is best known for his two-factor theory of intelligence, which posits a general intelligence factor, g, that underlies performance on a wide range of cognitive tasks, along with specific factors, s, that pertain to individual abilities. He contributed to the development of factor analysis as a method for understanding relationships among test scores and argued that positive correlations among diverse cognitive tasks reflect the influence of g. This framework laid the groundwork for quantitative approaches to measuring cognitive abilities.

In statistics, Spearman introduced the rank correlation concept, yielding Spearman's rank correlation coefficient (rho). This nonparametric measure assesses the strength and direction of a monotonic relationship between two variables by comparing their ranks rather than their raw values, making it robust to outliers and non-normal data.

The Spearman–Brown prophecy formula is another notable contribution in psychometrics. It provides a way to estimate how the reliability of a test would change if its length were altered, a principle widely used in test construction and evaluation.

Beyond these, the name Spearman appears in various scientific and academic contexts, but Charles Spearman’s contributions to psychometrics and statistics remain central to the field.