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I find differences in the fit results for four/five parameter fit between WorkOut and other systems.

Document ID: DQ122
Relevant to following products: WorkOut 1.5 WorkOut 2.0
Document description: Explanation: Differences in the fit results for four/five parameter fit between WorkOut and other systems.



It is likely that you will find small differences in results between WorkOut and other curve fitting packages. This is because different systems use different methods and you are not comparing like for like. In WorkOut the four and five parameter fits are calculated using Levenberg-Marquardt parameter optimisation and different systems will use different approaches (for example, one may decide it has found the best result when another may continue). WorkOut uses a multi-pass approach to ensure the best results, additionally WorkOut 2.0 allows you to specify the tolerance and maximum iterations parameters.

When comparing results with other systems you could consider the MSE as one measure to use to determine which fit results are better (the lower the MSE, the better the fit). Other “goodness of fit” measures are available in WorkOut 2.0.



Related articles:
DQ073: What is R˛?
What is R˛?

DQ074: What is SS?
What is SS?

DQ116: Is a Logit-log fit available?
Is a Logit-log fit available?





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