458 TRANSMISSION 



.SECTION III THE CORRELATION TABLE 



To determine the degree of correlation between any two 

 characters in any race, a so-called " correlation table " is con- 

 structed out of the measurements of the two characters as found 

 in a large number of individuals, one character being recorded 

 in columns and the other in rows. Two records are thus made 

 of the same individual, one for each character. Such a table, 

 when finished, consists of a double system of arrays, each 

 dependent on the other, and from whose means and standard 

 deviations the mutual relationships can readily be worked out. 



Knowing this relationship and the value of one of the char- 

 acters we are enabled to calculate the corresponding mean value 

 of the other. The advantages of this for purposes of selection are 

 obvious. The method is best illustrated by an actual example. 



For instance, it is evident that the weight of ears in corn de 

 pends partly upon their length and partly upon their circumfer- 

 ence. To what extent, for example, does it depend upon length ? 



In order to answer this question definitely a large number of 

 ears taken at random are both weighed and measured, and the 

 data are arranged in tabular form as described above, appearing 

 as follows : 



CORRELATION BETWEEN WEIGHT AND LENGTH OF EAR 

 (LEAMING CORN) 



WEIGHT OF EARS IN OUNCES 



