Dear all, I'm new in R and I need your help.

I have 40 patients treated.
During the pre-treatment patients respond to the experimental paradigm in the opposite way.
I find two categories of patients who respond to stimuli of the paradigm in the opposite way. And after treatment both subgroups of patients have opposite responses to the pretraining.

My question is: Can I make a Cluster Analysis? Could you tell me your book to understand the theory and how to use Cluster Analysis in R?
Thanks for your help and sorry for my bad English.

It is hard to tell from your description if cluster analysis is the best way to go.

To learn more about cluster analysis with R, I would start at http://www.statmethods.net/advstats/cluster.html. You can also find so good tutorials by doing a google search on the phrase "cluster analysis in R".

For a more general introduction to cluster analysis take a look at http://www-users.cs.umn.edu/~kumar/dmbook/ch8.pdf.

I hope this helps.

Rob

Dear Professor, thank you very much for your help. I had also written an email to thank you for your wonderful book "R in Action." I'm new to R and his book gave me such enthusiasm to learn.
Andrea