The use of quantitative methods in psychology is present essentially at its beginning as an independent discipline, and many of the early developers of statistical methods, such as Galton, Pearson, and Yule, are generally considered by psychologists as among the major contributers to the development of psychology itself. In addition, many early psychologists made major contributions to the development of statisical methods, often in the context of psychometric measurement theory and multivariate methods (e.g., Spearman, Thurstone). Among the techniques that psychologists developed or helped to develop during the early part of the twentieth century are the correlation coefficient, the chi-square test, regression analysis, factor analysis, principal components analysis, and various multivariate procedures. The use of the analysis of variance (ANOVA) in psychology did not begin until about 1940 and quickly became widespread.