TIME TO STANDARD EGG WEIGHT 5 



Correlation Between Winter Clutch Size and Time to Standard Egg Weight 



Mean winter clutch size is a very good measure of individual intensity. Further- 

 more, clutch size is governed by inheritance. Hays (1930) showed that the gene 

 for highest intensity is linked with a gene for small egg size. It seems desirable, 

 therefore, to determine by means of the correlation coefficient the relation between 

 winter clutch size and time to standard egg weight. The constants calculated 

 are as follows: 



Number of birds 383 



Mean winter clutch, eggs 3.49 



Winter clutch standard deviation ±1.31 



Mean time to standard egg weight, days 106.93 



Time to standard egg weight standard deviation ±48.33 



Coefficient of correlation +.3001 ± .0314 



The mean winter clutch indicates that the average individual carries the 

 highest degree of inherited high intensity, yet the variability in intensity is very 

 high. 



The simple correlation shows a positive association between clutch size and 

 time to standard egg weight. In other words, a little less than 10 per cent of 

 the variability in time required may be accounted for through variable intensity. 

 The regression is strictly linear. 



Determination of the partial correlation between clutch size and time required 

 gave the constant ri5. 234678 = +.1609, which indicates that less than 3 per cent 

 of the variation in time required is directly traceable to intensity variations. 



Correlation Between Winter Pause Duration and Time to Standard Egg Weight 



Winter pause as used in these studies means the cessation of egg laying for 

 four or more days between November 1 and March 1. In case there are several 

 periods of non-production, these periods are added together to arrive at the pause 

 duration. In the total population there were 146 birds showing no winter pause, 

 and these are omitted in calculating the correlation between pause duration and 

 time to standard egg weight. 



Number of birds 237 



Mean winter pause, days 27.07 



Winter pause standard deviation ±20.78 



Mean time to standard egg weight, days 106.04 



Time to standard egg weight standard deviation ±46.66 



Coefficient of correlation +.1340 ± .0430 



Duration of winter pause shows extreme variation in the population studied. 

 This fact suggests that there must be many influences affecting pause duration. 

 The data show further that the mean time interval for the pause birds is essen- 

 tially identical with the time interval for the entire population. 



The coefficient of correlation is positive but is not significant by Wallace and 

 Snedecor's (1931, loc. cit.) criterion, and is of such small absolute magnitude 

 as to be of little or no value as a guide in selection. The regression is strictly 

 linear. 



The net correlation between pause duration and time to standard egg weight 

 was —.0582, showing that little, if any, association exists between pause duration 



