# What is a good clustering fitness metric for DBSCAN?

Usually, my go-to goodness of fit for evaluating clustering (e.g., k-means) is the average silhouette.

However, for DBSCAN it doesn't work since there are lots of non-clustered points. So increasing the stringency of the parameters removes neighboring clusters, and therefore increases the difference between intra- and inter-cluster distance -- just because there are less points clustered.

What is a good clustering method for DBSCAN that takes into account this issue or is robust to number of points clusters?

• how about treating each non-clustered point as a single cluster? Jul 31 '18 at 4:05

The only measure that I know that takes noise points and density into account is DBCV:

Moulavi, D., Jaskowiak, P. A., Campello, R. J., Zimek, A., & Sander, J. (2014, April). Density-based clustering validation. In Proceedings of the 2014 SIAM International Conference on Data Mining (pp. 839-847). Society for Industrial and Applied Mathematics.

I haven't used it though.

@thc there is another paper worth looking,

Jaskowiak, P.A., 2015. On the evaluation of clustering results: measures, ensembles, and gene expression data analysis (Doctoral dissertation, Universidade de São Paulo).

It discusses in detail the validation of density based clustering methods including the DBCV suggested earlier. It also includes a rich discussion on related works and experimental evaluation.