90 The Opsoiiic Judex — A Medico-Statistical Enquiry 
result is that the probable error of the former will be greater than that of the 
latter. The coefficients of variation are 
Zero Index = 38-6, 
Avei-age Index = 25 "4. 
The actual detailed correspondence between the two is given in the following 
table from which we obtain a correlation coefficient of r = 0"76. 
" Average " Index. 
■0 
■s 
ro 
1-1 
1-3 
1-3 
1-4 
1-5 
1-6 
Totals 
•3 
1 
3 
1 
1 
6 
■k 
■5 
1 
1 
1 
4 
1 
2 
1 
5 
■6 
- 
1 
3 
1 
6 
5 
■7 
1 
2 
3 
2 
2 
10 
•8 
1 
4 
2 
2 
1 
10 
•9 
1 
4 
6 
2 
1 
16 
1-0 
2 
1 
3 
1 
10 
o 
1-1 
4 
1 
2 
7 
<s 
1-3 
2 
1 
3 
2 
8 
1-3 
1 
4 
5 
3 
1 
1 
6 
1-5 
1 
1 
1 
3 
1-6 
1 
2 
3 
Totals 
0 
1 
5 
4 
6 
17 
17 
12 ]7 
13 
1 
3 
100 
If we designate the " average index " by A and its mean value by A and the 
"zero index" by Z and its mean value by Z, we have as an equation connecting 
the two indices regarded as variables 
A=A + -5S (Z-Z)± -01, 
i.e. =-96 + -o3 (Z--91)±-01, 
and the degree of relationship between the one index and the corresponding mean 
value of the other is shown in the following table : — 
[Zero Index 
Average Index 
Calculated 
Observed 
■3 
■64 
■55 
■4 
•70 
■74 
■5 
■75 
■72 
■6 
•80 
•82 
■7 
■86 
■94 
■8 
■91 
•89 
■9 
■96 
•91 
1-0 
1-01 
1-01 
1-1 
ro7 
ro7 
1-2 
1-12 
1-06 
1-3 
1-17 
ri8 
1-4 
1-23 
1^25 
1-5 
r28 
1-40 
1-6 
133 
1-47 
