I believe SigmaPlot has additional trendlines.
best wishes
--
Bernard V Liengme
Microsoft Excel MVP
http://people.stfx.ca/bliengme
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"Don Culp" wrote in message
...
Are there any add-ins to Excel 2003 that include more trendlines?
Preferably
the add-in would have the option to search through its available
trendlines
to find the best fit for the specified data. I want this to work directly
inside Excel so that I don't have to export the data.

(I know that I can do this by entering a suspected regression equation in
the spreadsheet and then graphing the values generated by this equation.
However, this is too cumbersome especially if the form of the regression
equation is not known.)

Thanks,
Don Culp