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larity from month to month. These measures are naturally considerably 
larger than the average deviation without regard to sign. They range 
from 32.9 to 38.8 eggs. 
It is clear that the annual egg production of birds similar in origin to the 
series upon which the prediction equations were based and maintained un- 
der similar conditions may be predicted with a relatively high degree of 
accuracy providing their record for any month is definitely known. 
The order of the errors will be more readily understood by expressing 
them in relation to the average production of the flock, as shown by the 
percentage deviations. 
We note that in predicting from December, February and August records 
the average error with regard to sign is less than one per cent of the average 
annual yield of the flock. In predicting from November, January and 
March the error lies between one and two per cent. When April, May, 
June, July, September and October records are used as a basis of predic- 
tion the average errors of prediction are from 2.50 to 4.50 per cent of the 
average annual yield. 
The average deviations without regard to sign are less than 20 per cent 
of the annual production. The values for the individual months range 
from 15.7 for September to 19.1 for January. 
The square root of mean square deviation is less than 25 per cent of 
the average annual production. The individual values range from 20.9 
for September to 24.6 for January. 
These two latter tests may at first seem to indicate very unsatisfactory 
prediction. Such is not, however, the case. These give the average 
errors either above or below the true record made in the prediction of the results 
for an individual bird. The thing which is required in practise is generally 
the prediction for a group of birds of a particular grade of egg record for the 
month used as a base of prediction. In a flock of 415 birds this has been 
shown to be possibe with an error of less than 5 per cent of the annual produc- 
tion when prediction is made from the record of any month of the year; 
and with an error of less than 1 per cent when prediction is based upon the re- 
cords of a number of the individual months. 
Lack of space precludes a discussion of the results of the prediction of 
the annual record of the bird from the combined record of two consecutive 
months. We may, however, illustrate the accuracy of prediction from the 
combined record of two consecutive months by means of the figures in dia- 
gram 1 which shows the accuracy of prediction from November plus Dec- 
ember and from April plus May in comparison with the results of predic- 
tion from November and April. In these the estimated production is shown 
by a straight line. 
The actual production for the year for which prediction is made is shown 
by solid dots for each group of birds as classified by monthly or bimonthly 
