PREDICTING EGG PRODUCTION IN WHITE LEGHORNS 269 



mnual production from the record of the individual months were 

 riven. 



The results given in our second paper (HARRIS, BLAKESLEE and KIRK- 

 ATRICK 1917, 1918) show clearly that it is possible to predict with a 

 :onsiderable degree of accuracy the annual egg production of a group of 

 )irds from their record for a given month. They also indicate that it is 

 )ossible within limits to predict the egg production of any month, p, from 

 he egg record of any other month, q. 



Almost simultaneously CARD (1917) considered the correlation between 

 he records of various periods as a basis for the prediction of annual egg 

 production. Prediction equations were not, however, given. 



While, the determination of equations for the prediction of the egg pro- 

 luction of a subsequent or a more extended period from the actually 

 ecorded production of a limited period must rest upon biometric theory, 

 ve have deemed it proper in the testing of these equations to proceed in 

 L purely objective manner. 



We have determined a series of prediction equations and have used these 

 quations for estimating the egg production of a series of birds, the egg 

 ecord of which is unknown as far as the development of the equations is 

 ;oncerned. We then determined the difference between the yield pre- 

 ticted by the equations and the actual yield in the case of each individual 

 )ird. The average of these deviations, or any other suitable mathematical 

 onstant based upon them, furnishes a criterion of the suitability of the 

 quation for purposes of prediction. That equation is best which predicts 

 aost exactly the annual egg yield, or the egg production of any shorter 

 &amp;gt;eriod, for a bird of which the record of a limited period is known. 



Since the birds entered in the INTERNATIONAL EGG-LAYING CONTEST 

 t Storrs are drawn from a wide geographical area and are furnished by a 

 arge number of breeders, and since the conditions in the different years 

 re maintained as nearly constant as possible, it seemed desirable to utilize 

 ecords from this contest subsequent to those upon which the equations 

 re based in testing the value of the equations. The problem is: How 

 Josely can the actual production of a bird entered in the contest in a given 

 ear be predicted from equations based on the records of previous years 

 /hen one or more months performance of this bird is known from obser- 

 ation? We have, therefore, as already noted, based the test of our series 

 f equations first of all upon the records secured in Connecticut during the 

 ontest year 1917 and 1918. 



The equations which we publish are based upon 1840 single-comb White 

 -eghorn birds entered in the INTERNATIONAL EGG-LAYING CONTEST for 



EOTTICS6: My 1921 



