Hi, I'm analyzing GTEx data (read counts, ~30 patients, one tissue) to check if expression variability is different for 2 groups of genes (I'm interested in one special set on genes). With DESeq2 I estimate dispersion for each gene ("dispGeneEst" in DESeq2) that represents variability of expression between samples after removing the Poisson variability from sequencing.
I would compare dispersions betweens group1 and group2 but the problem is that these two groups have different mean levels of expression and dispersion is normally higher for low expressed genes. So I would see high dispersion of expression for group1 only because genes in this group have lower levels of expression.
Could you please suggest what test can be used here? I tried to sample genes from group2 so that they have "matched" expression levels but I wasn't able to get a subset of genes from group2 that would have the same distribution of levels of expression (tested by ks test). Any suggestions are appreciated! I work mainly in R.
I also attached scatterplot visualizing dependance between dispersions and mean levels of expression for 2 groups of genes.