Power and exponential trendlines in formulas

[Mr B]

Hi

Please help!!

I regularly produce response graphs for forecasting and use power and exponential trendlines to help plot future responses.

To speed up the process I really need to have my forecast equation linked to a cell.

I know it is possible to plot Linear x and y interception using the LINEST and INTERCEPT functions. Is there a function to plot power and exponential equations?

thanks

[Tim Francis-Wright]

On 2002-03-18 09:27, Mr B wrote:
Hi

Please help!!

I regularly produce response graphs for forecasting and use power and exponential trendlines to help plot future responses.

To speed up the process I really need to have my forecast equation linked to a cell.

I know it is possible to plot Linear x and y interception using the LINEST and INTERCEPT functions. Is there a function to plot power and exponential equations?

thanks

Youcan use the LOGEST function instead of
LINEST to use a logarythmic model. GROWTH
uses an exponential model. You can also
use the TREND function to use either a linear
or polynomial model.

Good luck!

[Mr B]

Thanks Tim, the GROWTH function helps.

Do you know how I can recreate a POWER trendline through a function? Or plot the interception point?

Thanks again for the earlier help.

[Tim Francis-Wright]

On 2002-03-19 09:03, Mr B wrote:
Thanks Tim, the GROWTH function helps.

Do you know how I can recreate a POWER trendline through a function? Or plot the interception point?

Thanks again for the earlier help.

There is no direct function to do this.
You can always use the standard transform
on the data and fall back on the LINEST function:

model
LOG(y)=LOG(B) + M LOG(X) linearly.

Someone clever on the web has probably got a free add-in with a POWER function that will
do exactly what you want.

Not that I know where. Good luck!

[sredfield]

I think I’m asking the same thing here, and wonder if there hav been any new discoveries in this area.

I’m using the power trend line formula to adjust data. I’d like to capture the “c” value and “b” value to plug into other formula’s, but don’t know how to extract it from the “add trend line, options, display formula on chart” series of selections so that it appears on the chart.

Is this even possible?


Thanks a gazillion.