In a related methodological context, Formann (1984) recommends a sample size
of at least 2m, where m equals the number of clustering variables. This can only
provide rough guidance; nevertheless, we should pay attention to the relationship
between the objects and clustering variables. It does not, for example, appear
logical to cluster ten objects using ten variables. Keep in mind that no matter how
many variables are used and no matter how small the sample size, cluster analysis
will always render a result!