70 



TECHNICAL BULLETIN 7 



16. Correlation Between Total Days Broody and December Rate — Pullet 

 Year. 



In this study the same group of 194.5 birds botii broody and non-broody that 

 were studied in relation of times broody to December rate (section 1) is con- 

 sidered. It is important to know which is the more important from the stand- 

 point of rate, the number of broody periods or the actual number of days 

 spent in l)roodiness calculated so as to avoid winter pause and fall molt. 

 Constants calculated on this group of birds follow: — 



Number of birds .... 



Mean total days broody 



Total days broody standard deviation 



Mean December rate 



December rate standard deviation 



Coefficient of correlation 



191.5 

 23.20 



±27.07 

 59.60 



It 20.40 

 +.0.529 



.0153 



The standard deviation in total days broody exceeds the mean total days 

 broody because of the large percentage of non-broody birds in the grouj) 

 studied. 



The coefficient of correlation agrees rather closely with the figure given in 

 section 1 where times broody and December rate are considered. Evidently 

 broodiness may be measured either by periods or iiy total days. The degree 

 of correlation is slight, and it is really a false correlation because based upon 

 a mixed population — broody and non-broody. 



17. Correlation Between Total Days Broody and December Rate for Broody 

 Birds Alone — Pidlet Year. 



The relation between degree of broodiness, as measured liy total days of 

 non-production associated with broodiness during the pullet year, and Decem- 

 ber rate may be determined by using only the birds that went broody the first 

 year. Such a determination was made for the same group of 94.9 birds that 

 was considered in section 2. The following are the constants: — 



Number of liirds .... 



Mean total days broody 



Total days broody standard de\'iation 



Mean December rate 



December rate standard deviation 



Coefficient of correlation —.0002 ± .0219 



Regression l^roodiness on rate 

 Regression rate on broodiness 



That degree of broodiness and December rate are entirely indeiiendent is 

 shown by the above coefficient of correlation which is practically zero. This 

 is rather conclusive evidence that December intensity bears no relation to tlie 

 ])resence or absence of the liroody trait. 



18. Correlation Between Total Days Broody and Winter Rate — Pullet Year. 



A total of 2221 birds studied in section 6 are included in this study to dis- 

 cover the degree of dependence or independence between total days l)roody 

 and winter rate. The constants calculated follow: — 



