I want to group my dataset using clustering technique. I apply k-means and used Dunn index and Silhouette Coefficient for the validation (selection of the best number of clusters). Now I want to know what should be the optimal cluster number based on the Dunn index. For your reference i am uploading the DI and SC plot ("cluster size" is the number of clusters).
The point is that if I keep on increasing the cluster no's the DI value is getting higher after 7. The minimum value in figure is 5. So can't we take 5 as the min no of cluster possible.
Please suggest what should be the cluster size i need to consider for this plot.