# Calculate Area Under the Curve

Can someone help me with the expression to calculate Area Under the Curve using this form **(NCY2 + NCY1) / 2*(NCX2-NCX1),** as a calculated column?

I am using the data below and have calculated the normalized cumulative sum of VarX (NCX) and VarY (NCY) and I would like to calculated the AUC below the curves NCX vs. NCY, for each Pump.

There are a couple of issues:

1. The fact that the dy and dx are variable, so therefore I need to make sure that I use the formula above and not an average or static dy/dx

2. Each pump has large volumes of data and I need calculate at such small intervals that at times, I am getting identical NCX or NCY values since they are the % cumulative sums.

Out of interest, If I wanted to perform the calculation by Pump and then by Zone, how would I include the zone qualifier as well? Most important is calculating by PUMP though,

Thanks!