Simple answer, yes, I think you understand where I was going with this - you would need to build the curve. So maybe this is not the route you want to take, I was trying to follow in the last post by Dan. As I mentioned, late to the party (o_-)
Looking back at OP:
You're saying that the second half isn't calculating, do you mean:
What I read here is:
Divide B.1.(Area) by 2
Add this value to
Is that what you intended to do? I suspect you want the calculated average of the areas between "A" and "B" in the denominator, this is a relative percent difference calculation - yes?
So lets start with that change and add an explicit grouping of the result:
(I've learned the hard way to explicitly group when working with databases, programing languages, etc... )
( ( A.1.(Area)+B.1.(Area) ) / 2 )
Explicitly group your first numerator:
( A.1.(Area)-B.1.(Area) )
Put these together along with 100 to get percent:
( A.1.(Area)-B.1.(Area) ) / ( ( A.1.(Area)+B.1.(Area) ) / 2 ) * 100
If you would like to give that a whirl (I've added a bit of spacing in there so that the eye doesn't get lost so a direct cut and paste may not work) and please let me know if we're on the right track.
I do not think you should need to have the "Summarize Custom Fields" selected in your sample set with this calculation; however, you might take a look at my thread here (this is the final post)http://www.chromforum.org/viewtopic.php?f=4&t=46831#p225394
As you can see in that thread, this simple thing gave me months of heartburn.