PREDICTING EGG PRODUCTION IN WHITE LEGHORNS 



295 



^rediction of the production of a group of remaining months from the sum of 



two monthly records 



We now have to consider the problem of the accuracy with which the 

 gg production of a group of subsequent months may be predicted from 

 tie sum of two consecutive monthly records. 



The equations are the following: 



Period jrom which prediction 

 is made 



November and December 

 December and January 

 January and February 

 T ebruary and March 

 Vtarch and April 

 Vpril and May 

 VTay and June 

 [une and July 

 luly and August 

 August and September 



Period for which prediction 

 is made 



January to October 

 February to October 

 March to October 

 April to October 

 May to October 

 June to October 

 July to October 

 August to October 

 September to October 

 October 



Prediction equation 



E= +132.887+ 1.160(e, + e 2 ) 



E = +128.112 + 0.979 (e 2 + ,) 



E = +124.959 + 0.336 (, + e t ) 



E = 

 E = 

 E = 

 E = 

 E = 

 E = 

 E= 



+76.542 + 1.320(&amp;gt;4 + e 6 ) 



+44.586+ 1.363 ( 8 + &amp;lt;) 



+25.022 + 1.231 (c + e 7 ) 



+7.280+ 1.118 (T +e 8 ) 



+0.994 + 0.827 ( g + ,) 



-7.281 + 0.660 (e, + e 10 ) 



-2.137 + 0.245 



The results appear in the second section of tables 5 to 7. Here they are 

 id beside the errors obtained for the prediction of the production of these 

 ime periods from the record of the two months individually considered, 

 3 given by the equations shown on page 282. 



Table 5, giving the average deviation with regard to sign of the predicted 

 om the observed values, shows that the actual deviations have a numerical 

 inge of 0.05 to 3.73 eggs or from 0.04 to 17.6 percent. The largest relative 

 percentage) deviations are, of course, in the final months of the year. 



The average deviations without regard to sign appear in the second 

 }lumn of table 6. These vary from as low as 5.13 eggs in October to 28.09 

 ?gs for the period January to October. Since the average production 

 ecreases as the number of remaining months becomes smaller we find 

 le largest percentage errors in the later groups of months. These per- 

 mtage values range from 18.9 for the period February to October to 87.4 

 &amp;gt;r the month of October. Similar results with somewhat different numeri- 

 il values are found in table 7 which shows the square root of mean square 

 aviation of the predicted from the observed values. 



These results show that when the number of remaining months is large, 

 rediction of egg production can be made with relatively high accuracy 

 om the combined record of two months. As the number of months 

 icomes smaller the error of prediction is, as compared with the average 

 reduction, relatively large. 



[ trencs 6: My 1921 



