How To Compute a Firm's Incidence Rate for Safety Management

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.

How to compute incidence rates

(a) The number of nonfatal injuries and illnesses. This number is available several ways:

• From your Log of Work-Related Injuries and Illnesses (Log), OSHA's Form 300--you can count the number of OSHA recordable cases for the year, or
• From your Summary of Work-Related Injuries and Illnesses (Summary), OSHA's Form 300A--you can add the number of recordable cases entered in columns H (cases with days away from work) + Column I (cases with job transfer or restriction) + Column J (other recordable cases),
• From the BLS Survey of Occupational Injuries and Illnesses form, if your company was surveyed for the calendar year for which incidence rates are desired--you can add the number of nonfatal recordable cases entered. Add the entries from Part 1B: Summary of Work-Related Injuries and Illnesses. Only include the entries in Column H (cases with days away from work) + Column I (cases with job transfer or restriction) + Column J (other recordable cases) in your calculation.

(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:

• From your Summary of Work-Related Injuries and Illnesses,
• From the BLS Survey of Occupational Injuries and Illnesses form, if your company was surveyed for the calendar year for which incidence rates are desired,
• From payroll or other time records.

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:

• 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).

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.

An example

The following discussion illustrates how ABC Company---a fictitious construction machinery manufacturing plant with 200 employees---might conduct a statistical safety and health evaluation.

The ABC Company has 15 injuries and illnesses logged and 400,000 hours worked by all employees during 2002. Using the formula, the incidence rate would be calculated as follows:

(15 x 200,000) / 400,000 = 7.5

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 7 such cases.

The incidence rate for these 7 cases is computed as:

(7 x 200,000) / 400,000 = 3.5

How are incidence rates used?

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.

In this example, the injury and illness rates for ABC Company are below the industry wide and similar-size averages for construction machinery manufacturing.

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 firm’s rates? The following table for construction machinery manufacturing firms employing 50 to 249 workers illustrates how these statistical measures work.

When ABC Company extends its rate comparison to these measures, the company finds that its total recordable rate (7.5) falls within the first quartile rate for construction machinery manufacturers of similar size, and its rate for cases with days away from work, job transfer, or restriction (3.5) falls between the corresponding first quartile and median rates for construction machinery manufacturers of similar size. In other words, both of ABC Company’s 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.

How do I obtain industry-specific data?

2002 incidence rates by quartile distribution and employment size group for:

Total recordable cases of injuries and illnesses (TXT) (PDF 229K)
Injury and illness cases with days away from work, job transfer, or restriction (TXT) (PDF 241K)
Injury and illness cases with days away from work (TXT) (PDF 248K)
Injury and illness cases with days of job transfer or restriction (TXT) (PDF 257K)
Other recordable injury and illness cases (TXT) (PDF 239K)
Total injury cases (TXT) (PDF 233K)

Last Modified Date: December 19, 2003

URL: http://www.bls.gov/IIF
Nonfatal summary information: (202) 691-6179
Nonfatal case and demographic information: (202) 691-6170
Fatality information: (202) 691-6175
Fax: (202) 691-6196
Fatalities questions: cfoistaff@bls.gov
Nonfatal injuries and illnesses questions: oshstaff@bls.gov