9 6 



BIOMETRY 



had 14 sons, whose heights are given in the first column. 

 The series of heights of sons corresponding to a par- 

 ticular class of fathers is known as an array. Thus 

 each column of the table represents an array of sons, 

 and similarly each line represents an array of fathers. 



62 



64- 



66 



68 



70 



72 



74- 



76 



62 



66 



68 



70 



72 



74 



76 



FIG. 9. DIAGRAM OF CORRELATION. 



The mode of each array of sons is given in the bottom 

 line of the table. 



Now if sons were on the average exactly the same 

 height as their fathers, the modal value of each array 

 of sons would be the same as the height of the corre- 

 sponding class of fathers. If, on the^other hand, there 



