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Michael Muratet
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@michael-muratet-3076
Last seen 10.2 years ago
On Mar 28, 2013, at 4:19 PM, Michael Love wrote:
> Hi Michael,
>
> The baseMean column is not on the log scale; it is the mean of
normalized counts for a gene. The intercept from the GLM is labelled
intercept in mcols(dse).
>
> Mike
>
Hello again
Here's a snippet of output for the "Intercept" term.
> head(res.mm9[["Intercept"]])
DataFrame with 6 rows and 4 columns
baseMean log2FoldChange pvalue
FDR
<numeric> <numeric> <numeric>
<numeric>
ENSMUSG00000000001 4160.27257 12.107650 0.000000e+00
0.000000e+00
ENSMUSG00000000028 127.54781 7.001754 0.000000e+00
0.000000e+00
and here's a snippet for two level factor
> head(res.mm9[["day14"]])
DataFrame with 6 rows and 4 columns
baseMean log2FoldChange pvalue FDR
<numeric> <numeric> <numeric> <numeric>
ENSMUSG00000000001 4160.27257 -0.06449054 4.578027e-02 1.042132e-01
ENSMUSG00000000028 127.54781 -0.05709357 3.020473e-01 4.500798e-01
I'm still unclear about how to write down the coefficients for the
model. The link function is log2(mean), correct? So is the
"log2FoldChange" the particular value of beta for that coefficient?
Would I write something like
y_tilde(ENSMUSG00000000001) = 12.11 - 0.06449 + other terms?
Thanks
Mike
> On Mar 28, 2013 5:00 PM, "Michael Muratet" <mmuratet at="" hudsonalpha.org=""> wrote:
> Greetings
>
> I have an experiment:
>
> > design(dse)
> ~ factor1 + factor2 + factor3
>
> where factor1 has two levels, factor2 has three levels and factor3
has three levels. I extract a gene of interest from the results for
each term (I've changed the indices to reflect the condition):
>
> > lapply(resultsNames(dse),function(u) results(dse,u)["gene_A",])
> [["Intercept"]]
> baseMean log2FoldChange pvalue FDR
> gene_A 1596.548 10.77485 3.309439e-216 7.025442e-216
> [["factor1_level2"]]
> baseMean log2FoldChange pvalue FDR
> gene_A 1596.548 0.3386776 0.1307309 0.3587438
> [["factor2_level2"]]
> baseMean log2FoldChange pvalue FDR
> gene_A 1596.548 -0.6882543 0.0613569 0.1007896
> [["factor2_level3"]]
> baseMean log2FoldChange pvalue FDR
> gene_A 1596.548 0.2393368 0.513216 0.6589575
> [["factor3_level2"]]
> baseMean log2FoldChange pvalue FDR
> gene_A 1596.548 0.1584153 0.6423634 0.8503163
> [["factor3_level3]]
> baseMean log2FoldChange pvalue FDR
> gene_A 1596.548 -1.627898 1.823141e-06 0.001409384
>
> I want to be sure I understand the output format. Is it true that
the coefficients (the vector beta) from the fit are the baseMean value
scaled by the log2FoldChange? Is the true intercept value
1596.548*2^10.77485=2797274.13?
>
> mcols() tells me that the baseMean term is calculated over "all
rows". The baseMean is different for different genes although it is
the same for each gene across all the conditions, I'm not seeing how
the rows are selected.
>
> Thanks
>
> Mike
>
> Michael Muratet, Ph.D.
> Senior Scientist
> HudsonAlpha Institute for Biotechnology
> mmuratet at hudsonalpha.org
> (256) 327-0473 (p)
> (256) 327-0966 (f)
>
> Room 4005
> 601 Genome Way
> Huntsville, Alabama 35806
>
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Michael Muratet, Ph.D.
Senior Scientist
HudsonAlpha Institute for Biotechnology
mmuratet at hudsonalpha.org
(256) 327-0473 (p)
(256) 327-0966 (f)
Room 4005
601 Genome Way
Huntsville, Alabama 35806