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I have two Excel charts:

Two Charts

How do I calculate area between these?

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If Series 1: were 22,22,20,20,22,22 and Series 2: 21,21,21,21,21,21 would you expect 3 or 1 as the result - and would crossing y=0 make any difference? –  pnuts Jan 8 '13 at 1:22

1 Answer 1

There's not such function built in as far as I know, but it's quite easy to perform a trapezoid integration on the data. Se here for example. I suggest you calculate the area for series 1 and series 2 and then subtract the two results.

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If the answer is 16.2 I don't think this solution achieves that (by the area under the three right hand series 1 points.) Because the points are equally spaced at unit intervals along the horizontal axis, the area under each adjacent pair of points is simply their average. –  pnuts Jan 7 '13 at 16:58
    
I'm not sure I understood your comment. Also, I don't understand why you removed "calculate integral" from the question which better explains what the user wants to do. In this particular example the area of the trapezoid is numerically equal to the average because the x spacing is 1, but this is not true in general. –  Pincopallino Jan 7 '13 at 17:12
    
As I understand it, the integral is the area under a curve bounded by the x-axis. That means there is a value for the area under the 3 RH points from Series 1 (but that is not an area between Series 1 and Series 2). "Calculate integral" seemed redundant to me but in any case I think the calculation is, strictly speaking, of the difference between two integrals. –  pnuts Jan 7 '13 at 17:19
    
Of course there is a value for the integral of series 1 from 1 to 3. I don't know what the user wants to do with the data but if he wants the area strictly between the two series he should start calculating the integrals from the point x=3. –  Pincopallino Jan 7 '13 at 17:32
    
I'd be happy to delete my comments if you wish to incorporate in your answer that for Series 1 OP should start calculating the integrals from x=3! –  pnuts Jan 7 '13 at 17:35

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