Xo. 628] 



EGG-WEIGHT 



386 



weight and then ascertaining the mean annual produc- 

 tion for each percentage-group. To make the matter 

 more clear both methods will now be applied— first to a 

 differentiation of the flock on the basis of production 

 groups. 



For the purposes of the present inquiry the flock^ may 

 be divided into two groups on the basis of the mean 

 annual production which was 120 eggs. One group was 

 made up of individuals whose production w^as above the 

 mean, and the other group included birds whose produc- 

 tion was below. The mean production of the plus group 

 was found to be 143 eggs, while the mean production of 

 the minus group was 99. After these production-groups 





= If: 









> 10 per cent. 











I 



J 



1- 



had been established tlu' nu nii ii.'t iiiciva-.- ur dccn'ase 

 increase fo^r the plus group was 5.4 per cent., and for the 



