PREDICTING EGG PRODUCTION IN WHITE LEGHORNS 275 



for the remaining months. The seventh shows the deviations and the 

 dghth the squares of the deviations of these predicted values from the 

 ictual record for the remaining months. 



Calculation blanks for each individual bird were made on this principle 

 ; or each of the equations used. The labor of testing the equation has, 

 ;herefore, been very heavy, involving the calculation of 29,465 predicted 

 /alues and the summations of the errors and squares of errors of the devi- 

 itions of these predicted records from their true value. 



The excessive arithmetical routine has been ably handled by Miss EDNA 

 VL PECKHAM, Miss IDA M. PECKHAM, Miss RUTH T. CRAWSON, and Miss 

 KATHLEEN GAVIN of the Biometric Laboratory of the STATION FOR EXPERI 

 MENTAL EVOLUTION. We are indebted to Miss EDNA K. LOCKWOOD for 

 he diagrams, as well as for much assistance in the computations. 



TESTS OF EQUATIONS EMPLOYED 



Prediction of annual production from the record of one month 



Consider first of all the results of the attempts to predict the annual egg 

 reduction of 415 White Leghorn birds observed at Storrs in 1917-1918 

 rom the records of a single month s production. The equations based 

 &amp;gt;n the 1911 to 1917 experience are as follows: 



Month from which prediction is made Prediction equation 



November E = +143 . 186 + 2 .914 e t 



December E = + 137 . 293 + 3 . 200 e 2 



January E = +138.271 + 3.308 e 3 



February E = + 1 18 . 689 + 3 . 926 e 4 



March = +76.160 + 4.708 e- a 



April E = +62 . 688 + 5 . 074 e 6 



May = +58.009 + 4.883 e 7 



June E= +59.977 + 4.818e 8 



July E= + 71. 137 + 4. 523 e 9 



August E = +90.391 + 3.974 fto 



September E = +118.509 + 3.381 e n 



October E = + 141 . 470 + 3 . 429 e a 





These are in good general agreement with the equations for two of the 

 ears, 1913-1914 and 1914-1915, published in a former paper (HARRIS, 

 ILAKESLEE and KIRKPATRICK 1918, page 33, table 5). The graphical 

 JSts for linearity of regression (loc. cit., diagrams 2-5, p. 34-39) for these 

 tfo years, indicate a fairly close approximation to linearity throughout 

 ie greater part of the range of variation of monthly egg production. A 

 :itical test of linearity presents some difficulties because of the concen- 



: My 1921 



