Trendline on only part of the data.

[donflak]

I have a chart with three years worth of weekly data points, 2 prior
years and the current year so I currently have approx. 128 data
points. I added a trend line. Again no problem. Know my boss wants
the trend line on only the current year or the last 24 data points as
it were.

Is there any way to trend only a portion of the data?

Thanks in advance for your assistance.

Don

 

[JLGWhiz]

Probably the easiest way is to set up a separate data series that calculates
the plot points weekly between the high and the low. The built in trend line
will span the entire series of data that you are tracking. A second, but
probably not so pretty, way would be to make the current year a separate data
series and put the built in trend line on it.

 

[Bernard Liengme]

Do you really need the trendline equation on the chart?
If not, then use LINEST to put the fitting values on the worksheet; you can
control which range of data LINEST uses)
LINEST works with many equations; see
http://people.stfx.ca/bliengme/exceltips/Polynomial.htm
http://www.tushar-mehta.com/publish_train/data_analysis/16.htm
http://spreadsheetpage.com/index.php/tip/chart_trendline_formulas/

If it must be on the chart: make a second series with the data be used for
the trendline; copy this; activate chart; used Edit | Paste Special ->New
Series to add this to the charts; add trendline to the new series

best wishes

 

[JLGWhiz]

When I was still working, I did presentations and our customer always wanted
trendlines so they could tell if the data indicated up or down. After all,
that is all a trend line tells you. So I prepared a set for our dry run,
before showing to the customer, and just put the words UP or DOWN on the
charts. My boss flipped out.
As Bernard pointed out, there are many alternatives to showing a trend line,
even just using the drawing tool to draw a line. Again. it only tells you up
or down.