DETERMINATION OF VARIATION 



103 



7. Determinations of variation. Variation in body weight and 

 organ weight. In table 58 Jackson ('13) gives a series of determi- 

 nations of the coefficient of variation for body weight on a litter 

 basis and in age groups. The animals were selected by the 

 method of 'random sampling.' These values are to be compared 

 with those determined by King (MS '15). In King's series the 

 same groups of rats were examined at different ages (table 67). 



For the same animals as were used in table 58 Jackson ('13) 

 also gives for the several organs the coefficient of variation 

 (table 59) and the coefficients of correlation with the body weight 

 (table 60). The coefficients of variation for body weight on age 

 are given by King (MS '15) in her growth series (table 67). 



TABLE 58. 



Coefficient of variation in body weight for total population by ordinary method, and 

 on litter basis (fraternal variation) estimated by various methods (Jackson, 'IS). 



Total population 



(ordinary method) 



Litter basis 



(average of litters calcu- 

 lated by ordinary me- 

 thod) 



Litter basis 



(calculated from Yule's 

 formula) 



Litter basis 



(from Kellogg' s 

 mula) 



for- 



18.5' 

 15.3' 



7.4 

 10.4 



8.1 

 9.3 



8.5 

 9.0 



1 For net body weight. 



1 For gross body weight, larger series. 



