How to Find Overall +/- Percentage Performance Over Several Quarters

[Jeff Earle]

I'm at a loss on this. I need to find the Overall +/- performance % of errors made over the 4 quarters of the year. I can get the performance +/- from the previous quarter but the overall is a mystery.

My data is:
1st 2nd 3rd 4th
50% 67% -55% -78%

Keep in mind that positive % = increase in errors & negative % = decrease in errors.

Also as time moves on I will be adding additional quarter % and want to show the entire history from the original 1st quarter.

Any help would be appreciated.

 

[BlueHornet]

You will have to revert your calculations back to the original data. You simply cannot "average" percentages in any meaningful way. If you do the same thing that you're doing quarterly (assuming that those results are valid!) but use the full year's data as the base set, then you can get to your answer, but counting or averaging percentages - though it can give "a number" - will not be a valid process.

 

[Jeff Earle]

You will have to revert your calculations back to the original data. You simply cannot "average" percentages in any meaningful way. If you do the same thing that you're doing quarterly (assuming that those results are valid!) but use the full year's data as the base set, then you can get to your answer, but counting or averaging percentages - though it can give "a number" - will not be a valid process.

I think I understand what your saying as I get erroneous % than does not look right. I have added the original data that might help:

Starting Errors	1st Qtr	2nd Qtr	3rd Qtr	4th Qtr
8	12	20	9	2
	50%	67%	-55%	-78%

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How do I show the overall +/- %?