In This Chapter

Chapter 9.
Occupational Safety and Health Statistics

Survey Measures
The number of injuries and illnesses are reported nationwide and by industry for three basic types of cases:

  • Lost workday cases,
  • Days-away-from-work cases, and
  • Nonfatal cases without lost workdays.

(Days-away-from-work cases, which may also involve restricted workdays, are a subset of lost workday cases, which include days-away-from-work cases and cases involving restricted work activity only.) For cases involving days away from work, the survey presents numeric and percent distributions by occupation and by the worker traits and four case characteristics defined in the preceding section. In addition, the survey includes two measures of severity for lost worktime cases: Median number of workdays lost and a percent distribution of days-away-from-work cases by their duration. The latter measures are presented nationwide, by industry, and for the aforementioned worker and case characteristics.

In addition to injury and illness counts, the survey also reports on the frequency (incidence rate) of such cases. Incidence rates permit comparison among industries and establishments of varying sizes. They express various measures of injuries and illnesses in terms of a constant, i.e, exposure hours in the work environment (for example, 200,000 employee hours or the equivalent of 100 full-time employees working for 1 year), thus allowing for a common statistical base across industries regardless of employment size of establishments. In this way, a firm with 5 cases recorded for 70 employees can compare its injury and illness experience to that of an entire industry with 12,000 cases for 150,000 employees. (The method of calculating incidence rates is discussed in a later section.)

Rates also are useful in evaluating the safety performance of a particular industry over time or in comparing State-to-State variations in an industry's safety record. Such comparisons are possible using the total case rate or the rate for lost workday cases, days-away from-work cases, or nonfatal cases that do not involve lost workdays. These measures are available for injuries only and for injuries and illnesses combined. For illnesses, rates are available for total cases and separately for the seven illness categories defined in the preceding section. Rates for days-away-from-work injuries and illnesses also are available for the various categories of the four case characteristics studied, for example, the incidence rates associated with carpal tunnel syndrome, back cases, injuries inflicted by health care patients, or disabling falls to a lower level.

Next: Scope of the Survey