Trend line in Excel

[deacs]

Hi all,

I'm messing around with the trend line function in excel. I see there are 6 different types of trend/regression types:

1. Linear
2. Logarithmic
3. Polynomial
4. Power
5. Exponential
6. Moving Average

I have a list with 30 data points that I would like to plot on chart with the different trend/regression lines. I notice that the Power and Exponential options are greyed out, so that I can not choose them. Is this because 2 of the 30 numbers are negative? Is there a way around this?

Thanks!

[Bernard Liengme]

That is correct
See also http://www.stfx.ca/people/bliengme/E...Polynomial.htm
--
Bernard V Liengme
www.stfx.ca/people/bliengme
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"deacs" <[email protected]> wrote in
message news:[email protected]...
>
> Hi all,
>
> I'm messing around with the trend line function in excel. I see there
> are 6 different types of trend/regression types:
>
> - Linear
> - Logarithmic
> - Polynomial
> - Power
> - Exponential
> - Moving Average
>
>
> I have a list with 30 data points that I would like to plot on chart
> with the different trend/regression lines. I notice that the Power and
> Exponential options are greyed out, so that I can not choose them. Is
> this because 2 of the 30 numbers are negative?
>
> Thanks!
>
>
> --
> deacs
> ------------------------------------------------------------------------
> deacs's Profile:
> http://www.excelforum.com/member.php...fo&userid=2321
> View this thread: http://www.excelforum.com/showthread...hreadid=511723
>

[deacs]

Thanks for the reply. Is there a way around this, so that I can plot the power and exponential lines? Must I remove the negative numbers?

The data points I have represent monthly costs and I would like to make projections based off of the raw numbers as reference points with other bottoms up projections. The months with negative numbers are months when there were returns within this cost category.

Thanks again for your help.

[Jay Somerset]

On Mon, 13 Feb 2006 09:34:28 -0600, deacs
<[email protected]> wrote:

>
> Thanks for the reply. Is there a way around this, so that I can plot the
> power and exponential lines? Must I remove the negative numbers?
>
> The data points I have represent monthly costs and I would like to make
> projections based off of the raw numbers as reference points with other
> bottoms up projections. The months with negative numbers are months
> when there were returns within this cost category.
>
> Thanks again for your help.


One way, although a bit clumsy, would be to add a constant to each number,
so that they are all positive. Plot your trend using whatever function you
choose, and then subtract the same constant from any projection that you
derive from the trend.