non-linear regression

[cuddy]

Version: 2004
Operating System: Mac OS X 10.3 (Panther)
Processor: Power PC

Hello,

Excel can perform linear regression, but I regularly need to perform regressions to a non-linear function (the sigmoid function). Any ideas for a plug-in or macro or something?

thanks!

 

[Carl Witthoft]

Version: 2004
Operating System: Mac OS X 10.3 (Panther)
Processor: Power PC

Hello,

Excel can perform linear regression, but I regularly need to perform
regressions to a non-linear function (the sigmoid function). Any ideas for a
plug-in or macro or something?

thanks!

Regress+

MatLab

ProFit

But for goodness' sake, if you're that deep into real math, run
screaming from Excel.

 

[Mike Middleton]

cuddy -

You can use the Solver in Excel 2004 for curve fitting.

Put tentative values of the function's parameters in cells, which will be
Solver's Changing Cells.

Put a formula for the fitted values of your function formula in cells,
referring to the parameter cells (e.g., absolute reference) and your data
points (e.g., relative reference, to ease copying).

Put formulas for deviation (difference between fitted and actual) and
squared deviation for each data point.

Put sum of squared deviations in a cell, which will be Solver's Target Cell.

Run Solver to minimize, perhaps also specifying some constraints.

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