Are these 2 runs of a K-means algorithm (on the same set of cases with the same variables) or (on the same set of cases with different variables) or (on different sets of cases with the same variables)? Do the runs look for the same number of clusters? if two points belong to the same cluster > in both clusterings this means that they are similar. If you have runs on the same set of cases and the same set of variables, CROSSTABing the memberships in the clusters will tell you exactly this. Art [log in to unmask] Social Research Consultants University Park, MD USA (301) 864-5570 Sirotkin, Alexander wrote: > Hello. > > From a few responses I got to my previous email I understand that I > did not formulate my question clear enough. > > What I meant by "compare two clusterings" is not to find out which > clustering is better - this information is usually provided by the k-means > algorithm in a form of within-cluster sum of squares. > > What I actually meant was a measure of how much these two clusters > are similar. In other words - if two points belong to the same cluster > in both clusterings this means that they are similar. > > Thanks a lot.... >