Voiv. 7, 1921 
GENETICS: J. A. HARRIS ET AL. 
219 
TABLE 3 
Errors oe Prediction of the; Record oe a Period of Months from the 
Record of Individual Preceding Months 
PERIOD FOR 
MONTH USED 
AVERAGE DEVIATION 
AVERAGE 
DEVIATION 
SQ. ROOT OE MEAN 
WHICH 
AS BASE 
WITH REGARD TO SIGN 
WITHOUT REGARD TO SIGN SQ. DEVIATION 
PREDICTION 
OE 
Actual 
Percentage 
Actual 
Percentage 
Actual 
Percentage 
IS MADE 
PREDICTION 
deviation 
deviation 
deviation 
deviation 
deviation 
deviation 
Dec.-Oct. 
November 
+ 2.39 
1 
.57 
29.59 
19.49 
38.65 
25.46 
Jan. -Oct. 
December 
+ 0.24 
0 
.16 
28.43 
19.53 
36.63 
25.16 
Feb -Oct. 
January 
+ 2.37 
1 
.71 
26.48 
19.06 
34.61 
24.91 
Mar.-Oct. 
February 
+ 0.09 
0 
.77 
24.07 
18.66 
30.86 
23.92 
Apr. -Oct. 
March 
— 0.24 
0 
.21 
22.81 
20.36 
28.40 
25.34 
May-Oct. 
April 
— 4.00 
4 
.23 
21.36 
22.59 
26.50 
28.02 
June-Oct. 
May 
4- 3.62 
4, 
.98 
19.89 
27.35 
24.81 
34.11 
July-Oct. 
June 
— 2.86 
5 
.34 
17.62 
32.91 
21.44 
40.04 
Aug.-Oct. 
July 
— 3.71 
10 
.43 
13.91 
39.09 
17.14 
48.17 
Sept.-Oct. 
August 
— 2.56 
13 
.57 
9.76 
51.75 
12.12 
64.26 
October 
September 
— 0.45 
7, 
,67 
4.57 
77.85 
5.71 
97.27 
The results of this investigation, taken as a whole, show that in the case 
of a flock of White Leghorn fowl which is essentially identical in genetic 
composition and maintained under essentially uniform conditions from 
year to year it is quite possible to estimate annual egg production from the 
record of either a single month or of two or three consecutive months with 
a high degree of accuracy. The same is presumably true of other breeds 
as well. This point is now under investigation. 
It is not possible to use the equations given in this paper for flocks differ- 
ing greatly in genetic composition or in conditions of maintenance from 
that upon which these equations were based. The problem of the deter- 
mination of corrective terms to be used when the equations are applied to 
flocks other than that upon which they are based is now under investiga- 
tion. 
A detailed account of these investigations is now in press in Genetics. 
*Alder and Egbert, Bull. Utah Agr. Exp. Sta., No. 162, 1918. 
2 Harris, Blakeslee and Warner, These Proceedings 3, 1917 (337-341); Harris, 
Blakeslee, Warner and Kirkpatrick, Genetics, 2, 1917 (36-77). 
3 Harris, Blakeslee and Kirkpatrick, These Proceedings 3, 1917 (565-569); 
Genetics, 3, 1918 (27-72). 
'A range of five eggs was used in order to obtain a number of birds sufficiently large 
to reduce somewhat the irregularities due to the errors of random sampling. The 
errors of prediction were in each case determined for classes of unit range. Grouping 
is used for graphic representation merely. The average deviations represented by the 
limit of the shaded zone are to be thought of as measured from a line perpendicular 
to the ordinates and intersecting the prediction line on the mid-ordinate of the 5-egg 
class. 
