In particular, the SMOTE-RF model gives the higher importance to chemical shifts than the other models, but all models are found in the same region (between 0.6 and 0.7). This means that most of the models' decisions are made based on the chemical shift (as an NMR spectroscopist would do). For tree-based models, it means that most nodes use chemical shift values to create branches. The sSMOTE-KNN model gives the highest importance to J-coupling values and integral values while the SMOTE-ET model gives a higher importance to splitting patterns.