Charles Edward Spearman (1863–1945) was an English psychologist and statistician who made foundational contributions to the scientific study of human intelligence and empirical methodology. Spearman is widely recognized as a pioneer of factor analysis, a statistical method used to identify underlying variables among observed correlation measures. He also developed Spearman's rank correlation coefficient, a non-parametric measure of rank correlation that remains a staple of modern statistical analysis. Beyond his methodological innovations, Spearman is highly celebrated for his seminal work on models of human intelligence. Through his statistical investigations, he proposed that individuals' scores across disparate cognitive tests reflect a single, overarching general intelligence factor. He coined the term 'g factor' to represent this shared variance, establishing a theoretical framework that would heavily influence subsequent psychometric testing and psychological research.
