area under the curve of a trendline

[Josh]

Does anybody know how to find the area under the curve of a trendline (6th
degree polynomial in my case).

Thanks in advance for any help.

 

[David Biddulph]

Please don't multipost.

Learn the difference between multiposting & crossposting:
http://www.cs.tut.fi/~jkorpela/usenet/xpost.html

 

[Josh]

I'm sorry about that, the browser did not change to the confirmation screen,
so I did not realize that the question was posted. On another note, do you
know of any answers to this question?

 

[David Biddulph]

The reason for not multiposting is that if you stick to one group the
question and the answers will all be in one place. If you look at your
other post you'll find at least two answers.

 

[Dana DeLouis]

Does anybody know how to find the area under the curve of a trendline
In general, here is one way...

Select 7 horizontal cells, and array enter the following equation:

=LINEST(Ys,Xs^{1,2,3,4,5,6},TRUE,FALSE)

I used Range Names to refer to the X & Y data located in columns.
This gives you the 7 coefficients,

In general, knowing that you equation is:
a+b*x+c*x^2+d*x^3+e*x^4+f*x^5+g*x^6

we take the integral to arrive at the following equation.

a*x+(b*x^2)/2+(c*x^3)/3+(d*x^4)/4+(e*x^5)/5+(f*x^6)/6+(g*x^7)/7

In two cells, set x to the upper limit, and lower limit of your range.
Subtract the two values to get the "Area."

 

[James]

What does

",Xs^{1,2,3,4,5,6}"

mean?