R help - Oct 2004 - plot hclust - canberra dist + median linkage

Gives strange results.

I get 'weird' dendrograms with canberra / binary distance metric and
median / centroid cluster methods.

Is this just my data?

Dan

>>>>> "Dan" == Dan Bolser <dmb at
mrc-dunn.cam.ac.uk>
>>>>>     on Mon, 11 Oct 2004 16:21:53 +0100 (BST) writes:
    Dan> Gives strange results.

    Dan> I get 'weird' dendrograms with canberra / binary distance
metric and
    Dan> median / centroid cluster methods.

it doesn't depend on the metric: 
Both 'median' and 'centroid' methods are known to *not*
guarantee ``monotone distance measures'', or equivalently to
possibly lead to dendrograms with so called ``inversions''.
We should add this to help page for hclust().

Probably for this reason, agnes() from the cluster package
doesn't have these two methods [explicitly] -- though it now
allows general parameter Lance-William formula methods which can
also lead to inversions.

    Dan> Is this just my data?

evidently not.  Though the problem does not appear for all data
sets...

Regards,
Martin Maechler