LII— LIII] 



Introduction, 



lxxix 



Illustration (ii). Consider the fourfold Table below and discuss the relative 

 probabilities that it has arisen from a population which shews 0, 1, 2, 3, etc. indi- 



viduals for this size of sample in the cell B, not-A. On the assumption that 

 is really the population of this cell, the probability is unity. Hence we have the 

 following result. 



Whence taking the a priori probabilities proportional to the probability of 

 occurring on the separate possibilities we have : 



Probabilities that the Table arose from a population 

 ivith x in the B, not-A cell. 



The " association " of such a Table cannot therefore be considered " perfect," for 

 in 37 °/ of cases it would arise from a Table with a unit or more in the B, not- A 

 cell. The above is actually a Table of the correlation of stature in father and son. 

 Grave caution is therefore needful in discussing such "perfect association" tables. 



Table LIII (p. 125) 



Angles, Arcs and Decimals of Degrees. (Based on Hutton's Mathematical 

 Tables.) 



This Table gives degrees in radians for the first two quadrants; it then gives 

 minutes and seconds from 1 to 60 in fractions of a degree and in radians. The 



