Sometimes this logic does not drop parameters which are unnecessary for a good fit, and user intervention will be required – or simply two models fit well to a specific region, and the spectroscopist would choose a model which was not preferred by the automatic fitter.
The figure shows a region where the algorithm chooses a significant step for the background, but one can suspect that another model without a step would also fit well to the measured counts.
To eliminate the step parameter from the region's fitted model, right-click the region. A popup menu appears now, providing the parameters that may be eliminated. Choose Drop Background Step menu item.
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HyperLab now eliminates the step, refits the region and displays the new fit.
The Chi-squared value increased (from 1.1 to 1.3), showing why the automatic fitter inserted the step previously.
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