Dimitris,
You need to look into multidimensional scaling (MDS). If you have the MASS4
book handy (Venables & Ripley) take a look at Chapter 11. There is a lot of
background materials and several examples.
You can also check out the CRAN task view on Multivariate Statistics under
"Principal coordinates / scaling methods" for some additional pointers.
Good luck!
-Christos
Christos Hatzis, Ph.D.
Nuvera Biosciences, Inc.
400 West Cummings Park
Suite 5350
Woburn, MA 01801
Tel: 781-938-3830
www.nuverabio.com
> -----Original Message-----
> From: s-news-owner@lists.biostat.wustl.edu
> [mailto:s-news-owner@lists.biostat.wustl.edu] On Behalf Of
> Dimitris Tambakopoulos
> Sent: Friday, March 09, 2007 12:00 PM
> To: s-news@lists.biostat.wustl.edu
> Subject: [S] discriminate groups of data
>
> Hi everyone...
>
> I need desperately some serious help here...
> and please forgive me for my English in advance.
>
> I have a database of 4 quantities measured from a large
> number of samples originating from different groups.
> I'm giving the above figure..
>
> sample(1) from group(1) quantity1 quantity2 quantity3 quantity4
> ...
> sample(i) from group(1) q1 q2 q3 q4
>
> sample(1) from group(2) q1 q2 q3 q4
> ...
> sample(i) from group(2) q1 q2 q3 q4
>
> sample(1) from group(i) q1 q2 q3 q4
> ...
> sample(i) from group(i) q1 q2 q3 q4
>
> hope this clears things up...
>
> I'm trying to discriminate the above groups as much as I can
> using the 4 quantities above in a 2D plot.
> I can take a pleasant discrimination by plotting a q1-q2
> scatter plot, but I have some overlaps that I would like to
> be eliminated.
>
> Is there a way to (pre)set the groups and calculate the new x
> and y (function of q1, q2, q3 and q4), which maximize the
> discrimination of the groups in a scatter plot?
>
> Please note that I'm not looking for the cluster analysis.
> I already know which are the groups and I would like to plot
> them together and discriminated.
>
> Thanks in advance
> Dimitris
>
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