Trend Line Equation Coefficients

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.

If you really are using an exponential fit < y=Aexp(Bx) > see
http://www.stfx.ca/people/bliengme/E...&%20LOGEST.htm
If you are using a power fit < y = Ax^B > then see the lower half of
http://www.stfx.ca/people/bliengme/E...Polynomial.htm
best wishes
--
Bernard V Liengme
www.stfx.ca/people/bliengme
remove caps from email

"Jake" <Jake@discussions.microsoft.com> wrote in message
news:4E860155-393B-45DB-994B-D221CE9DFA1D@microsoft.com...
> 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.

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

"Bernard Liengme" wrote:

> If you really are using an exponential fit < y=Aexp(Bx) > see
> http://www.stfx.ca/people/bliengme/E...&%20LOGEST.htm
> If you are using a power fit < y = Ax^B > then see the lower half of
> http://www.stfx.ca/people/bliengme/E...Polynomial.htm
> best wishes
> --
> Bernard V Liengme
> www.stfx.ca/people/bliengme
> remove caps from email
>
> "Jake" <Jake@discussions.microsoft.com> wrote in message
> news:4E860155-393B-45DB-994B-D221CE9DFA1D@microsoft.com...
> > 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.
>
>
>

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%



"Jake" wrote:

> 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.

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?
--
Bernard V Liengme
www.stfx.ca/people/bliengme
remove caps from email

"Jake" <Jake@discussions.microsoft.com> wrote in message
news:B5260451-3EA7-4D21-9FA9-3632DE3AB0E1@microsoft.com...
> 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%
>
>
>
> "Jake" wrote:
>
>> 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.