AMINA SHAHZADI, The eternal question.
What I do is that I generate a range of solutions, profile them on variables used to cluster the data into groups and any other information I have to profile the cluster groups on and then present the solutions to a group of others to assess meaningfulness, debate on the solutions and attempt to reach a consensus etc In many cases, eg, for algorithms based on k-means and hierarchical clustering, you are using an exploratory technique and there are no right/wrong answers to this Having used cluster analysis for years some things to look at because there is no way to answer this statistically (unless you are using a latent class type model with goodness of fit measures) are the following 1. What is the minimum size you believe to be robust for a single cluster (eg n=30, n=100) etc because the larger the number of clusters you generate relative to sample size, the smaller your clusters will be and there must be a cut-off point defined upon which you are not prepared to go any lower... 2. If you run the clusters through different algorithms, how comparable are the results (cluster stability) 2. What differences emerge between 2, 3, 4 cluster solutions etc (as you utilise larger numbers of clusters, does this still produce a meaningful result in that the clusters are distinct and unique, or are you just cutting larger clusters into smaller clusters without generating unique and usable information... Examine the clusters via a series of cross tabs (as you go from 2 to 3 to 4 cluster solutions) what happens to the members within clusters, are they distributed differently etc Thanks Paul ----- Original Message ----- From: "amna khan" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, November 02, 2007 2:19 AM Subject: [R] cluster analysis > Hi Sir > > How can we select the optimum number of clusters? > > Best Regards > > -- > AMINA SHAHZADI > Department of Statistics > GC University Lahore, Pakistan. > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
