Trend lines

K

katie_c

Select the data series that you want to add the trend line to. Either go to the Chart menu or right click to get to "add a trend line". This will take you through the process. Once the trendline is added, you can format it with the format palette.
 
T

Ted

Just upgraded from MAC Office 2003 to 2008.
What happened to TRENDLINE feature in Excel 2008. It was in Excel 2003.
 
M

Mike Middleton

Ted -

Add Trendline is available in Mac Excel 2008.

I entered two columns of data on a sheet and selected the data. I chose
Insert | Chart | XY (Scatter). I clicked on a point of the chart to select
the data series. I chose Chart | Add Trendline | Format Trendline | Type to
choose linear vs polynomial etc. and clicked OK.

Office 2003 was available only on Windows. Recent Mac Office versions are X,
2004, and 2008.

- Mike Middleton
http://www.DecisionToolworks.com
Decision Analysis Add-ins for Excel
 
T

Ted

Mike-
Thank you.
However, it's strange when you go to help and enter Trendline you get no useful response. I've been playing with Linear Regression on TI-83 and Numbers. Numbers doesn't seem to plot line for you as does TI and Excel 2008.
Is this the way to communicate back to an individual who posts a reply?
Ted
 
C

Cody

Has anyone checked to see if the trendlines you are generating in '08 are the same as '04? My students were coming up with way different slopes (for the best fit linear line) depending on the version of excel they were using. Is anyone else experiencing this and if so is there a good way to rectify it?
 
C

Carl Witthoft

Mike Middleton said:
Cody -

Please post an XY data set that exhibits this problem.

- Mike Middleton
http://www.DecisionToolworks.com
Decision Analysis Add-ins for Excel
Click to expand...

I strongly recommend using LINEST rather than trendlines. For one
thing, the fitting coefficients are in accessible cells, rather than
just a text box on a graph.

BTW, if you don't know this trick, you can fit any degree polynomial
using LINEST. That's because each power of x is othorgonal to the
others.
The basic form is

=LINEST([yarray],[xarray]^{1,2,3,4},true,true) e.g., for a 4th-order
poly. You need to enter it as an array formula, and to get all the
coefficients (plus R^2, residuals, and more), apply it to a 5colx4row
region. The number of columns is the polynomial degree plus one.
 
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