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%