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xzw102

USA
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Posted - 04/06/2005 :  5:28:27 PM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
In nonlinear curve fitting, if I choose "Statistical" in Weighting Method, why the fitting errors changes a lot depending on whether I check the "Scale Errors with Standard Deviation" or not?
If I want to get the ratio (like Mean +/- SD) of parameters from two fittings of different curves, Should I check it or not?

Leo_Li

China
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Posted - 04/07/2005 :  01:14:50 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
Dear Wang,
If "Scale Errors with Sqrt(reduced chi^2)" Check Box is selcted, Origin will multiply the reported error by the square root of the reduced chi-squared. This is why the fitting errors change.

You can find more information in Origih Help:
Analysis Curve Fitting | The Nonlinear Least Square Fitter | Starting the Fitting | Controlling the Fitting Procedure

Regarding how to present your fitting parameters (Mean +/- SE), I am not very sure whether the above option should be checked. But It seems better to uncheck it since you already have error bars for your data (i.e. statistical weighting).
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