| Davies-Bouldin |
 |
– |
The lower the better |
Internal metric based on a similarity notion between clusters. |
| DBCV |
|
[-1, 1] |
1 |
Internal metric for evaluating density-based clustering methods. |
| Dunn Index |
|
– |
The higher the better |
Trade-off between inter- and intra-cluster distances. |
| Silhouette |
|
[-1, 1] |
1 |
Trade-off between average inter- and intra-cluster distances. |
| Kolmogorov–Smirnov |
 |
[0, 1] |
1 |
Maximum difference between two empirical CDFs; close to 1 indicates highly dissimilar distributions. |
| Calinski–Harabasz |
|
[0, ∞) |
The higher the better |
Ratio of between- to within-cluster dispersion; higher values indicate well-separated dense clusters. |