As mentioned before, global fitting is important in chemistry because it allows for the simultaneous fitting of multiple datasets to a single model 117 , which can improve the accuracy and reliability of the model parameters. It is also important for complex models with many parameters, as it can help to reduce the risk of overfitting 118 and consequently misinterpreting. In combination with the goodness of fit statistics and correlation analysis, the user can statistically investigate the reasonability of the fit; in SI -Advanced Usage III, global fitting is utilized to empirically showcase the effect of covalency 77 on XAS spectra.