Hooker and Yule on Relative Importance: A Statistical Detective Story
William Kruskal · International Statistical Review · 1989
Summary In their 1906 J. R. Statist. Soc paper, R.H. Hooker and G.U. Yule present an approach to the relative influence of two variables upon a third in a multiple regression context. The primary formulas suggest that by 'relative influence' Hooker and Yule meant just the ratio of (partial) regression coefficients. Inspection of the numerical example and its text description, however, suggests something different, but not clearly described. Analysis strongly points toward regression coefficient times average (of independent variable) as the intended concept of relative importance. This sometimes-called 'level importance' is favored by economists because of its proportionality to elasticity. Hooker himself returned to the topic in 1907 and created fresh puzzles.