Trend Line Equation Coefficients

[Guest]

Is there a way to link to the coefficients of a trend line? I have some data
plotted with a exponential trend line fitted to it and the equation of the
trend line (y = cx^d) shown on the chart. Rather than manually copying c and
d to use them in another worksheet, I would like to link to them so that I
don't have to re-copy everytime my data changes. Can this be done?

Thanks.

 

[Bernard Liengme]

If you really are using an exponential fit < y=Aexp(Bx) > see
http://www.stfx.ca/people/bliengme/ExcelTips/ExponentialTrendline& LOGEST.htm
If you are using a power fit < y = Ax^B > then see the lower half of
http://www.stfx.ca/people/bliengme/ExcelTips/Polynomial.htm
best wishes

 

[Guest]

Cool, thanks. You're right - it's power fit, not exponential.

 

[Guest]

Actually, using this method gives me slightly different coefficients than the
numbers I got from the excel trendline equation. Any idea why?

Trendline:
a = 0.011
b = -0.433

Linest Equation
a = 0.014
b = -0.453

I only have 5 data points so might as well share those too:
1, 1.0985%
2, 0.7889%
3, 0.6603%
4, 0.6036%
5, 0.5432%

 

[Bernard Liengme]

My LINEST values are -0.4334173337 -4.5248442752

So my coefficients are
-0.4334173337 0.010836402

which are identical to those in the trendline equation.
I am using Excel 2003, what version are you using?