19(3 TECHNICAL BULLETIN 9 



This group of l)irds averaged about five and one-half pounds at first egg 

 and the extremes are 3 and 9.5 pounds, respectively. Class intervals of .5 

 pound were used in making these studies. AVeight shows a coefficient of vari- 

 ability of about 13 per cent. 



The coefficient of correlation exhiliits something of a tendency for light 

 weight and high persistency to move together. Such a coefficient might have 

 been anticipated from the fact that weight and age at first egg are positively 

 correlated (Hays, Sanborn and James, 1924.), and because hatching date and 

 weight at first egg are negatively correlated (Hays, Sanborn, and James, loc. 

 cit.). In view of these facts, it is doubtful if weight at first egg is a true 

 criterion of persistency. 



6. Correlation Beliu'een Body WeUjht at First Eijg Belozc the Mean and High 

 Persistency. 



Coefficient of correlation +.3161±.0132 



The above table j)resents the absolute correlation between weight at first 

 egg below the population mean and high persistency. Those birds weighing 

 less at first es:^ than the mean of the whole population may be considered 

 small while the high persistency class includes only those individuals laying 

 for 315 days or luore before molting. 



The coefficient of correlation is positive and of statistical significance. There 

 is a tendency for the persistent class to weigh less at first egg than does the 

 low persistency class. Although the correlation is significant, it is not pro- 

 nounced and probably does not imply that factors for rapid growth are in- 

 imical to iiigh persistency. 



7. Correldlion Between Net Winter Rate and Annual Persistency. 



In order to discover if there is any association l)ctween the net rate of lay- 

 ing throughout the winter season and persislency of laying the following fall, 

 a correlation table was made between winter rate and persistency, using the 

 2147 birds with records for both characteristics. The constants are as follows: 



Number of birds ....... 2147 



Mean winter rate 67.41 



Winter rate standard deviation .... ±8.87 



Mean annual persistency 302.98 



Persistency standard deviation .... ±59.03 



Coefficient of correlation -(-.1835±.0141 



Regression winter rate on persistency . . . -|-.028 



Regression persistency on winter rate . . . -|- 1.222 



