Entering edit mode
Hi all,
in relation to my mail from January this year, I followed Simon's
advice to
do my analyses in DESeq2 instead of DESeq.
I am working on an RNASeq from c. elegans. I have mapped the data with
the
ensembl genome build WBcel215. I have ran tophat2 to map and
featureCounts
to counts the reads (both with the defaults parameters).
I have two conditions, control and a knock-out with each three
replica. Now
I am trying to find differentially regulated genes between the two
conditions using DESeq2.
This is the script I am using to read my raw count table into DESeq2:
featureCountTable <- read.table("featureCountTable_RawCounts.txt",
sep="\t", quote=F)
colData <- data.frame(row.names=names(featureCountTable), condition =
c(rep("wt",3), rep("cpb3", 3)))
cds <- DESeqDataSetFromMatrix (
countData = featureCountTable,
colData = colData,
design = ~ condition
)
fit = DESeq(cds)
res = results(fit)
But I am getting the same problem with DESeq2 as I have got with
DESeq.
When I ran the DESeq command I get a warning:
Warning messages:
1: In log(ifelse(y == 0, 1, y/mu)) : NaNs produced
2: step size truncated due to divergence
So again I have tried to change the fitType.
fit = DESeq(cds, fitType="local")
Which than came back without any warnings.
The two dispersion plots can be found here
<http: s23.postimg.org="" pvopnmtxj="" desesq2_local.png=""> (local fit) and
here
<http: s23.postimg.org="" uk4pitj47="" desesq2_parametric.png="">
(default/parametric fit). The red line goes through the point-cloud in
both
cases (as Simon defined a good fit in the last communication, I wish
it
would have bin so easy :-) .
In the local fit type there a more outliers and the right end of the
slope
is going up again. I am not sure whether or not this is a good thing
or not.
So, my question is - which of the two options is better?
I understand, that in general the parametric (default) option is
better,
but here it gives me a warning, so that something in the fit
calculations
is not good.
How can I understand theses plots?
Thanks for the help
Assa
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