Question: Histogram of p values for all tests
0
gravatar for shivyasoni1994
4 months ago by
shivyasoni19940 wrote:

Hi, I am trying to do differential-gene-expression analysis with DESeq2, for that i have done pseudo-alignment using Salmon , and with tximport, gene-level abundance is calculated. I am following "Analyzing RNA-seq data with DESeq2", tutorial. I got Histogram of p values for all tests.

enter image description here

Please, guide me to interpret this plot. Can I proceed with the data, (for heatmap generation), showing above plot.

Thanks in advance!

rna-seq deseq2 • 392 views
ADD COMMENTlink modified 4 months ago by tw61730 • written 4 months ago by shivyasoni19940

Correct what? Please specify.

ADD REPLYlink written 4 months ago by ATpoint14k
1
gravatar for Nicolas Rosewick
4 months ago by
Belgium, Brussels
Nicolas Rosewick7.5k wrote:

Start reading this excellent article here : http://varianceexplained.org/statistics/interpreting-pvalue-histogram/

These two peaks at the right tail are strange. Did you use the nominal pvalue or the corrected one (you should use the nominal for the plot) ?

Otherwise the distribution seems to be anti conservative so it's good 😉

ADD COMMENTlink written 4 months ago by Nicolas Rosewick7.5k
0
gravatar for tw617
4 months ago by
tw61730
tw61730 wrote:

The two main patterns you should look for when interpreting p-value histograms are: a sharp spike near 0 ( like you have here) that drops off into a somewhat uniform distribution. This indicates that you have some significant differences. The other pattern would be a totally uniform (flat) distribution, this indicates no significant difference. Here it looks like you have the first and ideal pattern although those spikes near one are a bit weird. I think they are probably errors/genes with no or little reads that were not filtered out. Usually you should exclude genes with less than 10 total reads.

ADD COMMENTlink written 4 months ago by tw61730
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