TYPES OF INTENSITY 7 



Persistency is associated with winter clutch size in a positive manner and 

 regression is not hnear. The coefficient of correlation is +.1692 + .0130 and the 

 correhition ratio is .1927. The latter constant squared gives .0371 as the amount 

 of variance in persistency associated with variance in winter clutch size. 



Spring Clutch Size 



Since the spring season of March, April and May may be considered the nor- 

 mal laying period in the Temperate Zone, it is important to discover if the in- 

 tensity of laying at this time is associated with any of the four other characters 

 affecting egg yield. 



Table 1 shows that the correlation between age at first egg and mean spring 

 clutch is negligible. In other words, the age at which the pullet begins to lay 

 shows no relation to her spring intensity. The relation is linear, however. 



The regression of spring clutch size on winter pause duration is distinctly 

 non-linear by Blakeman's test. The correlation ratio shows that there is a posi- 

 tive relation amounting to .3596. Using the squared value of .3596 the constant 

 .1293 is obtained, showing the percentage of associated variability between 

 length of winter pause and size of spring clutch in 1156 birds with winter pause. 

 This association between duration of pause and subsequent rate of laying is 

 considered later in this report in connection with total days broody and summer 

 rate of laying. 



Total days broody during the pullet laying year is independent of spring clutch 

 size in Table 1. This appears in contrast to the significant positive correlation 

 between total days broody and mean winter clutch, already considered. 



Table 1 shows a linear correlation between spring clutch and persistency of 

 +.1539 ±.0160. This supplements the observation reported by Hays and San- 

 born (1926) that intense winter layers are more likely to be persistent layers. 



Mean spring clutch size is independent of age at se.xual maturity. The rela- 

 tion of spring clutch size to winter pause duration is fairly intimate though non- 

 linear. The degree of broodiness measured by non-productive broody periods is 

 independent of spring clutch size. The regression of persistency on spring clutch 

 size is linear and of some significance. 



March Clutch Size 



The usefulness of a short-time measure of intensity is clearly evident provided 

 such a measure accurately depicts the intensity for a long period. Mean clutch 

 size during March may be considered as a possibility. 



Table 1 shows no correlation between March clutch size and age at first egg, 

 duration of winter pause, total days broody in the broody population or annual 

 persistency. Clearly the rate of laying in March is independent of the four 

 inherited characters just mentioned. The regression of March clutch size on the 

 four above-mentioned characters is strictly linear by Blakeman's test. 



April Clutch Size 



The correlation coefficient indicates complete independence between mean 

 clutch size during the month of April and age at first egg, duration of winter 

 pause and total days broody. The regression is strictly linear in all cases. 



The correlation between April clutch size and annual persistency is of low 

 degree and the regression is linear. The amount of variance in April clutch size 



