Hallam, I'll try. Remember that MATs are a way of trying to smooth out month on month fluctuations. On 1st Jan the MAT is the total of the past 12 months i.e. Jan to Dec of the previous year. At the end of Jan you deduct the total for Jan of the previous year and add the total for the month of Jan that has just finished. You still have a total of 12 monthly figures comprising Feb to Dec of previous year plus Jan of this year. At the end of Feb you deduct the Feb figure from the previous year and add in the total for Feb of this year. And so on.... Hope this helps, Phil

Now there's a question... I'm not 100% sure . However, the general rule is that you can't add up indices, percentages etc. So I woudl guess that you will need to add up the two componeents separately. Thus generate a MAT for reportable accidents, then a MAT for the manhours and divide one by the other to calculate your AFR. Perhaps someone else will confirm.. Phil

However, Phil is right, the average annual rate isn't the same as the average of the monthly rates over the year. To find the average of X/Y, you have to divide the total X by the total Y over the whole period. So in this case the number of accidents over the twelve months, by the number of hours worked (and stick in whatever multipliers you are using). A spreadsheet would still be the easiest way to do it though - add up the figures for the monthly periods, then divide them.