Abstract The Advanced Isoconversional (AIC) method involves minimization of a function which uses conversion data at a minimum of three heating rates to determine an activation energy ( E a ) at different values of conversion ( α ). Reactions that can be described by a single model give an E a which is independent of α , while reactions which are described by more than one model give an E a which varies with α . Shifts in the conversion curves due to error can lead to E a vs. α trends which falsely indicate, or mask, true multi-model kinetics. It was found that the minimum value obtained during optimization of what we call the ‘Optimization Indicator’ ( Ω ) can indicate whether trends in E a vs. α are likely to be error-derived in the case of single-model reactions or artifacts in the case of multi-model reactions. E a and Ω for the calcination of CaCO 3 are used to demonstrate the experimental application of this new diagnostic.