Table 3. Best-Performing Single Variable Classifiers by 5-Fold Cross-Validation and Prediction on an External Test Set^a.

descriptor	cross-validation accuracy (%)	external validation accuracy (%)
nConf20	85.9	86.1
valence electron count	78.1	78.4
Kappa1	78.3	78.3
Chi0n	78.3	77.9
SlogP VSA2	77.7	77.8
Kappa2	77.8	77.8
Kier molecular flexibility index	77.3	77.6
path length flexibility index	75.2	75.2
rotatable bond count	73.9	74.8

^aExisting flexibility descriptors²⁷ are included for comparison.