Posted By Robert K Lewis Liam If you have read your book correctly them I am afraid you might as well call the units orange-apples. The formula you provide is mixing units of time unless it is trying to give you the number of days lost per hour worked which seems a bit odd. Severity to me is a measure of the average number of days lost per accident ie total days lost/total accidents causing loss You can also look at the median figure for time loss as a general measure of severity Can you provide more information concerning your needs and no doubt some of the maths whizzes among us will be able to provide a formula. Bob

Posted By Martin Ffitch I am willing to be shot down in flames...BUT : I think that this formula is giving you % lost time using the assumption that workers do a 10 hour day.

Posted By Martin Ffitch Yes - But that is where the assumption that the workers are doing a 10 hour day comes from. No. of man hours worked / 10 = No. of Man days worked. The formula then becomes a straightforward ratio between those days lost and those days worked. Multiply the fraction by 100 and you have %. I'm not trying to justify it - but that's my guess at how it's working! M

Posted By Kevin Walker According to an Amercian Workers Compensation site:: In nearly all cases, time away from work drives the cost of losses more than any other determinant. This is why modified duty plays such a vital role in controlling costs. Therefore, the severity rate, which measures lost time, becomes the single best non-economic indicator of the overall effectiveness of a company’s workers’ compensation program. So, what is it, and how do we calculate it? The severity rate is the number of days away from work due to workplace injury or illness per 100 full time employees (FTEs) per year. It sounds daunting, but the Department of Labor has made it easy to get and use this data. To calculate your severity rate, divide the total number of days lost due to occupational injury or illness by the total number of hours worked by all employees. Following this, compare your severity rate with the average for your Standard Industrial Classification (SIC), published annually by the BLS. Remember, the average for your SIC is nothing more than the middle of the bell curve; it is neither good nor bad. You should set for your company a goal of maintaining a severity rate that is 50% less than your industry’s average. there you go simple isn't it, still no wiser kevin

Posted By Barry Cooper Liam I work for a global company and the stats they use are as follows Lost Time Injury frequency rate (LTIFR) No of lost time accidents per 200,000hrs = No. lost time accidents in period x 200,000 / No of hours worked in period Lost Time Injury Severity Rate (LTISR) No of lost hours per 200,000hrs = Number of lost hours in period x 200,000 / No of hours worked in period We also have Injury Index (II) = LTIFR x LTISR (which is just an index number) We then report to the paper fed our accident rate = No of reportable accidents x 1000 / Number of employees This is the number of accident per 1000 employees I the wonder what all this has to do with safety. You are better off measuring the things you do to prevent accidents, as when you are measuring the above you have failed. Try measuring number of near misses, safety observations, audits etc per audit hour or similar