TYPES OF INTENSITY 9 



C. SHORT-TIME MEASURES OF INTENSITY IN RELATION TO 

 ANNUAL EGG PRODUCTION 



Table 1 also includes the correlation coefficients showing the relation between 

 six measures of intensity and annual egg records. 



The regression of annual egg production on winter clutch size is distinctly 

 non-linear by Blakeman's test. The correlation ratio with a value of .4214 

 supplies a true measure of association. The magnitude of this constant squared 

 is .1776 showing that 18 per cent of the variance in annual production is due 

 to variance in winter intensity. For selection purposes, winter clutch size does 

 furnish a significant criterion of annual egg record. 



Annual production does not show linear regression on spring clutch by Blake- 

 man's test. Therefore, the correlation ratio of .5024 with a positive sign expresses 

 the true relationship. By squaring this constant .2524 is obtained to ex-press the 

 amount of variance in annual production that may be attributed to variance in 

 spring clutch. Spring clutch size has, therefore, a high value in selecting for 

 intensity. 



The three months: March, April and May, making up the spring season all 

 show non-hnear regression of production on clutch size. In these data, April 

 clutch size appears to be the most significant with a correlation of .3975, followed 

 by May with .3498 and March with .3023. No single month in the spring season 

 appears to give as good a measure of intensity as the combined three months. 



Regression of annual production on summer clutch size is non-linear and the 

 correlation ratio is .4238. This constant squared gives .1796 as the part of the 

 variance in annual record associated with variance in summer clutch. This 

 constant indicates that summer clutch size is of somewhat less importance than 

 spring clutch size for the flock studied in so far as annual egg records are concerned. 

 There is a possibiHty that spring clutch size has been reduced by the methods of 

 selecting for high winter intensity and for greater persistency. 



In a general sense, no one of the six short-time measures of intensity may be 

 considered as an accurate criterion of the clutch size for the year. For the flock 

 studied, spring clutch size is the best short-time measure. These data suggest 

 that eight distinct types of intensity may occur: 



Winter Spring Summer 



High High High 



High High Low 



High Low High 



Low High High 



High Low Low 



Low Low High 



Low High Low 



Low Low Low 



Section A shows that high spring and high summer intensity are more likely 

 to occur together than high winter and high spring or high winter and high sum- 

 mer. The same section also presents a significant correlation for intensity be- 

 tween any two of these seasons. In selecting breeders for maximum intensity, 

 therefore, the clutch size throughout the first laying year offers the only rehable 

 guide. 



