I'm trying to evaluate what is the right number of cluster needed for clusterize some data.
I know that this is possible using Davies–Bouldin Index (DBI).
To using DBI you have to compute it for any number of cluster and the one that minimize the DBI corresponds to the right number of cluster needed.
The question is:
how to know if 2 clusters are better than 1 cluster using DBI? So, how can I compute DBI when I have just 1 cluster?