[R] cluster results using fanny

Barbara Diaz bdiaz10 at gmail.com
Fri May 13 20:55:17 CEST 2005


Hi,

I am using fanny and I have estrange results. I am wondering if
someone out there can help me understand why this happens.

First of all in most of my tries, it gives me a result in which each
object has equal membership in all clusters. I have read that that
means "the clustering is entirely fuzzy". Looking at the graphics it
is really difficult to understand how objects with so different scores
for the variables have the same membership for all the clusters.

I also find estrange the fact that if I set K=3 (three clusters), it
gives membership for all three clusters (0.333 for all of them) and
then when it gives the closest hard clustering they only belong to
cluster 1 or 2, but none of them to cluster three. The plot shows only
two clusters (also the silhouette plot, even if it gives in the
"silhouette plot information" the silhouette width for the three
clusters????????.

Then, for the same data I set k=4 and surprisingly, it gives
membership for the four of them (this time they are not all the same)
and when it gives the closest hard clustering they only belong to
cluster 1, 2, or 3 but none of them to cluster 4. The plot shows only
three clusters (also the silhouette plot, even if it gives in the
"silhouette plot information" the silhouette width for the four
clusters????????. why didn't it give this three clusters when I set
k=3??????

For k=5 it gives all the information and then it only plots 2 clusters.

This is very confusing. Also, if there is equal membership for all the
clusters, how is it that I have a "closest hard clustering"? and a
"neighbor"?

Thank you in advance,

Barbara




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