294 



HARRIS, KIRKPATRICK, BLAKESLEE, WARNER AND CARD 



The differences in the average deviations with regard to sign, as sho? 

 in the first of the two final columns of table 2, range from less than a sinj 

 egg (5 comparisons) to a maximum of less than 7 eggs. The avera 

 difference is 2.21 eggs. If signs be considered the average difference 

 only + 0.67 eggs. The differences in the percentage deviation when predi 

 tion is made by single- and by two-month periods are shown in the fir 

 column of the table. 



o 2 4 e 



10 /2 14 IB IB 20 22 24 ^S 28 30 32 34 3ff 38 40 42 44 46 48 SO S2 54 St 



DIAGRAM 8. Tests of prediction of annual production from the combined record of two cc 

 secutive months. Tests of August to October. 



It is clear from these results that the results of prediction from tw 

 months production are not materially better from the practical stan 

 point than those for single-month s production although the labor entaili 

 in recording the performance of a bird for two months must be appro? 

 mately twice as great as that for a single month. 



The reader who cares to do so may verify these statements by a st 

 of the results for average deviation without regard to sign and for sqi 

 root of mean square deviation as shown in the two final columns of tat 

 3 and 4. 



