| Index name (abbreviation) | Method | Optimal value | Reference |
---|---|---|---|---|
External | Adjusted Rand Index (ARI) | Rand index adjusted for chance | Max (\(=1\)) | [11] |
indices | Fowlkes-Mallows index (FM) | Sensitivity and precision | Max (\(=1\)) | [12] |
 | Normalized Mutual Information (NMI) | Information theory | Max (\(=1\)) | [13] |
Internal | Calinski-Harabasz index (CH) | Within/between-cluster variance | Max | [14] |
indices | Connectivity index (Connectivity) | Clustering consensus of nearest neighbors | Min | [15] |
 | Davies-Bouldin index (DB) | Within/between-cluster distance | Min | [16] |
 | Dunn index (Dunn) | Within/between-cluster distance | Max | [17] |
 | Baker-Hubert Gamma index (Gamma) | Within/between-cluster distance | Max | [18] |
 | SD index with average scattering (SD-Scat) | Within/between-cluster variance | Min | [19] |
 | Silhouette index (Silhouette) | Within/between-cluster distance | Max | [41] |
 | Xie-Beni index (XB) | Within/between-cluster distance | Min | [20] |