THE MEASURE OF COMPARATIVE PRODUCTIVENESS 317 
Standing in 
Production in terms 
Attendance 
Men 
Tests 
of t earned per hr. 
% 
A 
98 
70 
97 
B 
96 
69 
95 
C 
95 
68 
80 
D 
92 
66 
99 
E 
87 
64 
93 
F 
81 
63 
90 
G 
76 
6l 
92 
H 
69 
59 
99 
I 
62 
55 
84 
J 
53 
53 
87 
IO 
809 
628 
916 
Av. 80.9 
Group Av. 62.8 
Av. 91.6 
It is evident from the above figures that there is a 
satisfactory degree of correlation between the records in 
the tests and in production. The men who were highest 
in the tests were, on the whole, highest in production, 
and vice versa. If we apply the formula, familiar to 
statisticians, and explained in Chapter II, we would 
obtain plus .60 as the index of correlation, and this is a 
rather high index. If there were no close correspondence 
between the test and production records, the correlation 
would be expressed in a much lower figure, for example, 
plus .08 or even a minus quantity such as minus .62. 
Thus it becomes possible to determine with mathematical 
exactness just what degree of correspondence exists be 
tween these two factors, and to tell what the success of 
the selections has been. 
If, now, it becomes necessary to lay men off for lack of 
work, unsuitability, or any other reason, the employment 
manager can determine, by referring to the employee’s 
activity record, whether or not the right men are being 
laid off. For example, let us suppose that A, C and J on