Incidence rates can be used to show the relative level of injuries and illnesses among different industries, firms, or operations within a single firm. Because a common base and a specific period of time are involved, these rates can help determine both problem areas and progress in preventing work-related injuries and illnesses. The Bureau of Labor Statistics (BLS) has developed these instructions to provide a step by step approach for employers to evaluate their firm's injury and illness record.
BLS also has an online calculator that makes it easy to compute incidence rates for your establishment and to compare them to your industry's averages.
(a) The number of nonfatal injuries and illnesses. This number is available several ways:
(b) The number of hours all employees actually worked. "Hours worked" should not include any nonwork time, even though paid, such as vacation, sick leave, holidays, etc. If actual hours worked are not available for employees paid on commission, by salary, or by the mile, etc., hours worked may be estimated on the basis of scheduled hours or 8 hours per workday. This number is also available from several sources:
An incidence rate of injuries and illnesses may be computed from the following formula:
(Number of injuries and illnesses X 200,000) / Employee hours worked = Incidence rate
(The 200,000 hours in the formula represents the equivalent of 100 employees working 40 hours per week, 50 weeks per year, and provides the standard base for the incidence rates.) You can use the same formula to compute incidence rates for:
NOTE: When comparing illness rates by types of illness, use 20,000,000 hours instead of 200,000 hours to get a rate per 10,000 full-time employees.
- Injury and illness cases with days away from work (Column H),
- Injury and Illness cases with job transfer or restriction (Column I),
- Injury and illness cases with days away from work, or job transfer or restriction, or both (DART) (Column H + Column I),
- Other recordable injury and illness cases (Column J),
- Injury-only cases (Column M1),
- Illness-only cases (Column M2 + M3 + M4 + M5 + M6).
The following discussion illustrates how ABC Company-a fictitious construction machinery manufacturer with 200 employees-might conduct a statistical safety and health evaluation.
The ABC Company has 7 injuries and illnesses logged and 400,000 hours worked by all employees during the year. Using the formula, the incidence rate would be calculated as follows:
(7 x 200,000) / 400,000 = 3.5
The same formula can be used to compute the incidence rate for the most serious injury and illness cases, defined here as cases that result in workers taking time off from their jobs or being transferred to another job or doing lighter (restricted) duties. ABC Company had 3 such cases.
The incidence rate for these 3 cases is computed as:
(3 x 200,000) / 400,000 = 1.5
Incidence rates take on more meaning for an employer when the injury and illness experience of his or her firm is compared with that of other employers doing similar work with workforces of similar size. Information available from BLS permits detailed comparisons by industry and size of firm.
The following tables illustrate how detailed comparisons can help a firm evaluate its safety and health experience more precisely.
|Incidence rates for construction machinery manufacturers||Total recordable cases of injuries and illnesses||Injury and Illness cases with days away from work, job transfer, or restriction|
|All workforce sizes||4.5||2.2|
|Firms with 50 to 249 employees||6.5||3.0|
|ABC Company (200 workers)||3.5||1.5|
In this example, the injury and illness rates for ABC Company are below the industry wide and similar-size averages for construction machinery manufacturers.
Information available from BLS goes beyond giving the average incidence rate for a particular industry and employment-size class: Data show how individual establishment rates within an industry-size combination are distributed.
Points on these rate arrays, called the first quartile, median, and third quartile, help answer the following question: What proportion of comparable employers have rates that are lower than (or higher than) my firms rates? The following table for construction machinery manufacturer firms employing 50 to 249 workers illustrates how these statistical measures work.
|Incidence rates for||Total recordable cases of injuries and illnesses||Injury and Illness cases with days away from work, job transfer, or restriction|
|Average (mean) for all establishments||6.5||3.0|
|First quartileOne-fourth establishments had a rate lower than or equal to||1.9||1.4|
|MedianOne-half of the establishments had a rate lower than or equal to||4.9||1.7|
|Third quartileThree-fourths of the establishments had a rate lower than or equal to||11.3||4.7|
When ABC Company extends its rate comparison to these measures, the company finds that its total recordable rate (3.5) falls between the first quartile rate and the median rate for construction machinery manufacturers of similar size, and its rate for cases with days away from work, job transfer, or restriction (1.5) falls between the corresponding first quartile and median rates for construction machinery manufacturers of similar size. In other words, both of ABC Companys rates are lower than the rates for at least one-half of the medium-size construction machinery manufacturers. This analysis reinforces earlier findings that ABC Company has a lower incidence rate of injury and illness in its workplace than do most other construction machinery manufacturers of its size.
Incidence rates by quartile distribution and employment size group for:
Last Modified Date: March 25, 2019