# Cluster analysis for few data points

I have a question regarding cluster analysis.

I was wondering if I have only 9 data points, is it valid to use k-means methods in cluster analysis?

I have done a special molecular evolution analysis and it has generated 9 points, what I want to know is that whether there is any clustering among the groups. What I did was to just assign numbers to 3 groups and then do ANOVA and post-hoc t-test, but I was wondering if there is a more appropriate method for that?

Thanks.

• What data have you got about these nine points? – Peter Flom - Reinstate Monica Dec 14 '13 at 16:26
• It's unclear to me what you mean by "points," "groups," and "numbers." You 'have' 9 data points; the analysis 'generated 9 points'; you are interested in 'clustering among the groups'; and you 'assigned numbers to 3 groups.' Clarification would probably bring you more answers. – rolando2 Dec 15 '13 at 4:46

You can afford to use the most expensive clustering algorithm (most linkage variants are in $O(n^3)$) if $n=8$; it's only for really large data sets where k-means shines because of its linear runtime.