196 



TECHNICAL BULLETIN 9 



Tills group of birds averajred 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. Weight shows a coefficient of vari- 

 ability of about 13 per cent. 



The coefficient of correlation exhibits something of a tendency for ligiit 

 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. 



(). Correlation Beticeen Bocli/ Weit/bt at First Eijcj lieloxv the Mean and Hi<ih 

 Persistency. 



Coefficient of correlation ..... 4~-3161it.01.'32 



The above table presents the absolute correlation between weight at first 

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

 less at first egg 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 more 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 ])ersistcncy class. Although the correlaticn is significant, it is not pro- 

 nounced and probably does not im])ly tiiat factors for rapid growth are in- 

 imical to high persistency. 



7. Correldliori BetTveen Net Winter Rate and Annua} Persistencij. 



In order to discover if there is any association between the net rate of lay- 

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

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

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



Number of birds .... 

 Mean winter rate .... 

 Winter rate standard deviation 

 Mean annual persistency 

 Persistency standard deviation 

 Coefficient of correlation 

 Regression winter rate on persistency 

 Regression persistency on winter rate 



2147 



()7.41 



±8.87 



302.98 



±59.n3 



-f-.1835±.0141 

 -f.028 

 +1.222 



