Simulated Mössbauer spectra of Lorentzian form have been fit with proper and improper models over a wide range of signal/noise (S/N) ratios in order to evaluate the characteristics of the goodness-of-fit parameters x2 and misfit as a function of sample concentration and run duration. Results demonstrate a marked difference in behavior, x2 may be reduced, suggesting an improved fit, if an incorrectly fit spectrum is degraded in quality. This is not the case with misfit. However, misfit may be defined in two slightly differing ways, each of which “diverges,” to large negative and positive values, respectively, at small S/N ratios. Failure to allow for these characteristics can lead to fundamental misinterpretations of an effect like “spectrometer drift” or the estimation of optimal data collection conditions.

The application of x2, misfit, and Δmisfit parameters to fit evaluations in mineralogical spectroscopy is reviewed in light of the differing parameter responses.

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