[BioC] unnormalised vs normalised distribution

botto b.otto at uke.uni-hamburg.de
Thu Jun 8 14:23:45 CEST 2006


Dear list members,

I've been looking at the distribution plots of pm intensities and the
corresponding expression values calculated by gcrma for a certain data
set. Now I'm wondering what the best interpretation of these plots would
be, because the former looks quite usual while the latter seems quite
"unfamiliar" to me (nearly like a bimodal distribution, a jpg file
should be attached). The data measured is simply the expression for
certain mouse tumor tissues. Can anybody explain why after the
background correction and normalisation I get this distribution shape?

log(PM) density:

|      *
|    *  *
|   *    *
|  *     *
|  *      *
| *        *
|*          *
|             ***********
+-------------------------------

gcrma-expression values:

|      *
|    *  *
|   *    *
|  *     *
|  *      *
| *        *     * * *
|*          ****       *
|                        ***
+----------------------------------





-- 
Benjamin Otto
Universitaetsklinikum Eppendorf Hamburg
Institut fuer Klinische Chemie
Martinistrasse 52
20246 Hamburg


More information about the Bioconductor mailing list