118 The Danger of Certain Correlation Formulae 
the value of the coefficient of association when r is small and by a small increase 
when r is large. 
It is not difficult to give some striking instances of the effect of neglecting the 
fact that the value of the coefficient of association is entirely dependent on the 
choice of axes. Tims in dealing with Dr Warner's data in the Phil. Trans, paper 
already cited, Mr Yule gravely discusses the " apparent law that associations were 
on the whole higher where populations were healthier or less defective." But we 
Scale of Correlation. 
Fig. 6. Diagram to show the relative values of (1) Mr Yule's Coefficient of Association, 
(2) Mr Yule's "Theoretical value of r " and (3) the actual value of r, when /i = fc = 3-09. 
