136 MAIXE AGRICULTURAL EXPLRIMEXT STATIOX. I909. 



These coefficients t cf. p. 134 ) indicate that the present statis- 

 tics show in general a sensible correlation between the winter 

 s&fe laying and the j^er cent, of fertile eggs hatched during the 

 hatching season. The correlation coefficient for 1908 is roughly 

 4 times its probable error, while that for 1909. all birds included, 

 is 2.4 times its probable error. The 1909 pullets alone show a 

 very low coefficient, which, taken by itself, could only be regard- 

 ed as not significantly cift'erent from zero. It, however, is nega- 

 tive like all the other coefficients. There is little doubt that this 

 1909 pullet correlation would have been higher, had there been 

 data from a larger number of birds. All the figures taken 

 together indicate with a high degree of probability that there 

 is a real and significant relationship between the phenomena 

 shown by the statistics. The negative sign of the coefficients 

 indicates that the relation is of the sort that the higher the 

 zvinter egg 'production the lozcer is the percentage of fertile eggs 

 hatched and vice versa. 



Putting all the results together the present statistics show 

 that while the high winter layer is not essentially different from 

 the poor winter layer in regard to the fertility of eggs she is 

 on the average distinctly inferior in respect to the hatching 

 quality of her eggs. The hen that has laid heavily during the 

 winter produces during the hatching season fewer viable chicks 

 from a given number of fertile eggs. 



The Fertility axd Hatchixg of Eggs ix' the Pullet axd 

 « Secoxd Year of Life. 



In this section we have to do with the questions raised in 

 paragraph 5 of the statement of problems in the introduction. 

 The questions were : To what extent are the fertility and 

 hatching quality of her eggs innatel'^unchangeable characteristics 

 of a bird? If a pullet produces eggs shown above the average 

 for pullets in either fertility or hatching quality, will the same 

 bird's eggs in the second year of life -be above the average for 

 yearling hens in these respects? 



To answer these questions it will be clearly necessar}- to appeal 

 again to the method of correlation. Correlation tables must 

 be formed which have, to take fertility of eggs as an illustra- 

 tive case, as one variable the percentage eggs infertile in the 

 pullet year, and as the other variable the percentage of the 



