86 SAFETY AND PRODUCTION
few or have been materially reduced. As an example, a new process
or machine may reduce the number of men required to turn out a
certain output from 100 to 10, but may somewhat increase the hazard
per exposure hour. The net result, however, is a much less aggregate
danger to the 10 men than to the 100; but this fact would not be
shown so clearly by a comparison of accidents per exposure hours as
by a comparison of accidents per unit of product.
100
of
3(
4"
nes or
» Pg
2
2
h
~~ Severity Rate per
\ 10,000 Pairs
1921
108.5
19 9
1922 1923 1925
62.9 80.5 66.7 82.0
Accidents per 10,000,000 Pairs
1.71 1.82 4.25 : 3.80
Days Lost per 10,000 Pairs
CHART 40 AccmENT FREQUENCY AND SEVERITY RATES IN TERMS OF PRODUCTION
FroM 1921 10 1926 oF 3 CoMPANIES MANUFACTURING BooTS AND SHOES. NUMBES
oF EMPLOYEES, 1,681
Accident frequency rate decrease .....................21.0 per cent
Accident severity rate decrease. . vers sssannnd3O 0%