Figure For following up on the development of the final fitting model of complex 1, the corresponding metric is highlighted in the middle with its metric AIC (green), BIC (purple), and MSE (orange) for model validation. The corresponding plots for iteration steps 0 (initial guess model), 3, 7, 8, and 12 (final model) are shown. The complete set of plots from 0 to 12 can be found in the SI. At first, it may seem that all five fits represent the spectrum. However, the number of used distributions and models must be verified, which is why SpectraFit's metric is an essential tool for selecting a reasonable model based on statistics. Comparing the residuals of models 7 and 8 can help the user understand that both models might look equally good. However, the metrics clearly indicate that model 8 is more accurate and reasonable. Additionally, an increase in distributions leads to a further improvement in the fit of the final models. In summary, this complex figure serves as a guide for using the metric plot during fitting optimization. Adapted from Ref. ; Copyright 2023 America Chemical Society (ACS).