[BioC] How would I normally compare swirl?
michael watson (IAH-C)
michael.watson at bbsrc.ac.uk
Wed Jun 2 15:26:23 CEST 2004
Hi
I have a dataset which is pretty much IDENTICAL to the swirl dataset:
Experiment 1 - two replicate arrays with a dye swap:
TreatedCy5 vs UntreatedCy3
UntreatedCy5 vs TreatedCy3
Experiment 2 - two replicate arrays with a dye swap:
TreatedCy5 vs UntreatedCy3
UntreatedCy5 vs TreatedCy3
This is fantastic because I can basically just copy and paste the
instructions from the limma userguide.pdf document to get my
differentially expressed genes.
However, I want to do a comparison of limma with a "normal" method of
analysis - say a t-test. How would I carry out a t-test on this kind of
data?
For example, the top gene limma pulls out has these values for my four
arrays for log2(Cy5/Cy3):
-2.7, 2.7, -2.7, 3
This makes sense as the experiment contains a dye-swap, so if I flip my
log(ratios) such that I am always comparing treated/untreated, my values
are -2.7, -2.7, -2.7 and -3. BUT how would I go about doing a t-test on
this kind of comparison??? (I know there are huge arguments against
doing such a thing, but humour me). I mean, I basically have four
values for the same thing (the relative expression of treated against
untreated) and if I was doing a t-test - what am I comparing the values
against?
Thanks in advance
Mick
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