I have a small toy example. I have a treated and untreated samples from RNA-seq experiment. I calculated fold changes treated/untreated (Assuming, I have only one treated and one untreated sample and I want to look at the genes that are upregulated in the treatment, so fold changes >1). The values are not normal distributed, they are more like from extreme distribution. And now I want to calculate p-values or some kind of significance-value. Zero hypothesis is that there is no different in treated vs untreated, so the fold change will be 1.
Below is a of the distribution of a fold change of treated_sample_1 / untreated_sample_2 (vertical line is at 1). So, not being strict, I would tell that all genes above >1 are up-regulated in treatment vs non-treatment. But I need some kind of a significance value how far are they from 1. Is it possible to calculate a p-value out of it?
I could standardize it, so that the mean=0 and sd=1 but it still would not be normally distributed (plot below). From z-scores I could obtain p-values like 2*pnorm(-abs(z-scores)) but I do not think it is appropriate.
