Incident Rate Calculations practice questions for the CHST exam
CHST5 Domain 3: Safety Program Development, Implementation, and Sustainment (S3.3 Identify trends related to incidents; K3.7 Recordkeeping). 4 free questions below. Every answer quotes and links the formula source it rests on.
A manufacturing plant logged 24 OSHA-recordable injury and illness cases last year. Its 280 employees worked a total of 540,000 hours. What is the plant's total recordable incidence rate per 100 full-time workers?
Show answer and source
Answer: B. 8.89
Incidence rate = (N x 200,000) / hours worked = (24 x 200,000) / 540,000 = 8.89. The 200,000 base represents 100 employees working 40 hours a week for 50 weeks. Using 100,000 as the base would give half the correct value.
“(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.)”
A manufacturing plant logged 8 OSHA-recordable injury and illness cases last year. Its 120 employees worked a total of 238,000 hours. What is the plant's total recordable incidence rate per 100 full-time workers?
Show answer and source
Answer: D. 6.72
Incidence rate = (N x 200,000) / hours worked = (8 x 200,000) / 238,000 = 6.72. The 200,000 base represents 100 employees working 40 hours a week for 50 weeks. Using 100,000 as the base would give half the correct value.
“(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.)”
A warehouse recorded 20 OSHA-recordable cases in a year: 4 with days away from work, 5 with job transfer or restriction only, and 11 other recordable cases. Employees worked 160,000 hours. What is the DART rate (days away, restricted, or transferred) per 100 full-time workers?
Show answer and source
Answer: B. 11.25
DART uses the same formula as the total recordable rate but counts only cases with days away, restriction, or transfer: (4 + 5) x 200,000 / 160,000 = 11.25. Including the 11 other recordable cases gives the total recordable rate instead.
“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.”
A warehouse recorded 18 OSHA-recordable cases in a year: 6 with days away from work, 2 with job transfer or restriction only, and 10 other recordable cases. Employees worked 150,000 hours. What is the DART rate (days away, restricted, or transferred) per 100 full-time workers?
Show answer and source
Answer: A. 10.67
DART uses the same formula as the total recordable rate but counts only cases with days away, restriction, or transfer: (6 + 2) x 200,000 / 150,000 = 10.67. Including the 10 other recordable cases gives the total recordable rate instead.
“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.”
Unlock every CHST question with timed practice, the AI tutor and full-length mocks. Or start with the free diagnostic.
Related topics
Original practice questions, not real exam items. PassCited is not affiliated with or endorsed by BCSP.