Egon S. Pearson 
65 
VII. ExPEiuMENT B, Bisection. Reductiox of Observations. 
(a) Tlie individual Series. 
In this Experiment the coefficients of correlation of successive judgments for 
the individual series were not all worked out, but only the values of ; these are 
tabled with and di in Table IX. The values of d^ for each series, k—1 ... 14 
are also given in Table X. It will be seen that there are not the same marked 
secular or sessional changes as characterised the Trisection Series. In Figure 9 
the means of Groups 1 of each Series — or the c^i's— have been plotted to " order " 
and to " time," and again if 
X is the personal equation or mean, 
y the number of order of series, 
z the number of days between 13th June and the date on which the series 
was carried out, 
we have for the regression lines 
X - 2-8793 = - -0010131 {;j - lO'S) (xxxiv), 
X - 2-8793 = - -0005359 {z - 32-10) (xxxv). 
These lines have been drawn in the diagrams ; the coefficients of correlation 
are 
r^, = - -337 ± -1:34, = - -156 + '147, r,,, = f "945 ± '016, 
giving partial correlations 
?>/.^ = + -529 ±-109, „ ---589 + -099. 
TABLE IX. Constants of Bisection Experiments. 
Dates (1920) and time 
at start 
Series 
Pi 
'^6 = '^1^^2(l^pi) 
for 
series 
Probable 
Errors 
of 
uoejjicients of uorre- 
I 
II 
III 
2-8648 
-8624 
•9262 
-04997 
-05461 
-03821 
+ •4942 
+ -2609 
+ -0823 
-0503 
-0664 
-0518 
11 a.m.) , T 
,-, > 13 J une 
2.45 p.m-i 
p.m. 15 ,, 
gm 0^ 
5 20 
5 45 
lation calculated from 
50 pairs of the vari- 
IV 
-8642 
•04690 
+ -4107 
-0509 
10 a.m.( ,„ 
3p.m.S^^ " 
a.m. 30 ,, 
5 
30 
ates. 
V 
•8290 
-05158 
+ -5870 
-0469 
5 
45 
VI 
•9114 
-04609 
+ -5768 
•0424 
5 
45 
VII 
VIII 
•9178 
•9218 
-04415 
-04766 
+ -2993 
+ -4360 
•0523 
•0506 
10 a.m.) 1 , , 
12.15 p.m.! ^J^ly 
5 
6 
45 
0 
p 
p. E. 
IX 
•8724 
•04384 
+ -1389 
-0575 
10.30 a.m.) c, 
5 
30 
X 
•8990 
-04579 
+ -1018 
-0614 
6.30p.m.( " " 
6 
15 
-80 
± -0343 
XI 
•9238 
-03617 
- -0423 
-0522 
9.30a.m.j p 
6.45 p.m.) " 
6 
30 
•70 
+ -0486 
XII 
•9298 
•04810 
+ -5089 
-0477 
6 
45 
•60 
+ -0610 
XIII 
•8806 
-04407 
+ -2769 
-0530 
a.m. 7 ,, 
5 
45 
•50 
+ -0715 
XIV 
XV 
-8312 
•8242 
•04955 
-03606 
+ -4445 
+ -3334 
-0522 
■0416 
11 a.m.) , . , 
r, } 1 August 
2.30 p.m.j 
6 
6 
45 
15 
•40 
•30 
+ -0801 
+ -0868 
XVI 
•7976 
■04135 
+ -3190 
-0483 
p.m 16 ,, 
•20 
+ -0916 
XVII 
•8566 
■03739 
+ -5531 
-0353 
a.m. 17 „ 
•10 
+ -0944 
XVIII 
•8808 
•03497 
+ -2776 
-0420 
p.m. 18 „ 
1 
-00 
+ -0945 
XIX 
•8890 
•03986 
+ -5407 
-0382 
p.m. 19 „ 
0) 
XX 
2-9030 
•02610 
+ -1404 
•0342 
p.m. 20 ,, 
Mean time taken for a series of 70 observations (including the 7 preliminary trials *) 5"" 58> 
Mean interval between records of judgment 5-11^ 
* See p. 28, footnote. 
Biometrika xiv 5 
