132 MAINE AGRICULTURAL EXPERIMENT STATION. I909. 



Examining these tables it is seen at once that there is no such 

 evident correlation between the two characters as there was in 

 the case of fertility and hatching quality of eggs. If there is 

 any sensible influence of winter egg production on the fertility 

 of eggs it obviously cannot be a very marked one. The indi- 

 viduals are apparently scattered over the table a good deal at 

 random. There is no general trend of the statistics evident to 

 the eye to indicate a close relationship between these phenomena. 

 However, as has been seen before, the only way to determine 

 the nature and degree of relationship is to calculate the coeffi- 

 cient of correlation between the variables. Doing this for 

 Tables IX to XII inclusive we get the following results. 



Coefficient of correlation between winter egg production and 

 percentage of infertile eggs during the breeding season : 



1908. r = 0.077=1=0.064. Pullets only. 



1909. r = — 0.032=1=0.056. Pullets and yearling hens com- 

 bined. 



1909. r = 0.108=1=0.072. Pullets only. 



1909. r = 0.009=1=0.089. Yearling hens only. 



From these values it is apparent that the present statistics 

 indicate no correlation whatever between winter egg 'production 

 and fertility of eggs during the hatching season. The correla- 

 tion coefficient itself is not sensibly larger than its probable 

 error in either year and hence cannot be regarded as signifi- 

 cantly different from zero. A hen with a very high winter 

 production is on the average no more likely to have her eggs 

 run low in fertility than is a hen whose winter production has 

 been lower, and vice versa. As before no wider generality is 

 claimed for this result than arises from the statistics upon 

 which it is based. All that is asserted is simply that when very 

 careful records were kept during the whole hatching season for 

 over 200 birds and over 10,000 eggs the returns show no rela- 

 tion whatever between winter laying and fertility of eggs. 



