Karl Pearson is best known for the statistic that bears his name the "Pearson Product-Moment Correlation Coefficient". (Those of you who are not endeared to statistics are probably now cursing his name).

His major contribution to psychology has been as the 'grandfather' of rigorous statistical evaluation of human behavior. Apart from correlational analysis, Pearson developed the chi-squared statistic with intellectual (and financial) encouragement from Galton. Together these analyses were (and still are) essential components leading to multivariate statistical analysis. Outside psychology, Pearson's interest in biological questions heralded the development of the field currently known as "bio-statistics".

In collaboration with Galton, Pearson founded the now prestigious journal Biometrika. With Pearson as editor, however, the journal was notorious for its extreme bias and unauthorized revisions of submitted works. It just goes to show that people (even statisticians) are not 'perfect'.