188 TECHNICAL BULLETIN II 



NuMber of birds 3863 



Mean age at first egg 206.14 



Age at first egg standard deviation ±29.47 

 Mean net winter rate 67.79 



Winter rate standard deviation ±8.86 

 Coel/icient of correlation ■ — .2274 ±.0103 



A moderate degree of negative correlation is found between age at first 

 egg and winter rate of laying. Evidently there is some tendency for the 

 early maturing pullets to lay somewhat more intensely than do the late 

 maturing individuals. This difference is no doubt due to larger clutch size 

 in the earlj- maturing birds as has been pointed out in section 4. The fact 

 should be noted here that the degree of correlation is identical between 

 age and clutch size and between age and net winter rate. 



10. Correlation Between WeUjlit at First Ef/fi and Net Winter Rate. 

 Mature body weight in poultry is inherited on a Mendelian basis accord- 

 ing to Punnett (1923). Weight at first egg has been shown by Hays, 

 Sanborn and James (1924) to depend both upon hatching date and upon 

 age at first egg. If there is any relation between weight at first egg and 

 winter rate of laying, body weight might be used as a partial criterion in 

 selection. To gain this information the constants below were determined: 



Number of birds 3794 



Mean weight at first egg 5.53 



Weight standard deviation ±.72 



Mean net winter rate 67.81 



Winter rate standard deviation ±8.82 



Coefficient of correlation — .1756 ±.0106 



The above coefficient of correlation is of the same magnitude as was 

 the coefficient of correlation reported in section 5 between weight at first 

 egg and winter clutch size. Again the correlation coefficient is statistically 

 significant but of little practical value for prediction and selection pur- 

 poses. 



11. Correlation Between Winter Egg Production and Net Winter Rate. 



To discover the relation between net winter rate and winter egg record, 

 the population of 3863 birds is studied. The following constants appear: 



Number of birds 3863 



Mean winter production 62.95 



Winter production standard deviation ±25.92 



Mean net winter rate 67.79 



Winter rate standard deviation i ±8.86 



Coefficient of correlation +.5444 ±.0076 



The above constants indicate an intimate positive correlation between 

 winter rate and winter production. This correlation points rather con- 

 clusively to the importance of winter rate as a factor in winter egg pro- 

 duction. Since winter rate is inherited (Hays, 1924), it becomes evident 

 that one important means of securing high winter production lies in the 

 development of a high winter intensity strain. 



