I have detected some interesting epigenetic regions on the genome (for example, differentially methylated regions) and I have some features on the genome (for example, I classify all the genome to 3'UTR/5'UTR/gene body/promoter/enhancer/junk region).
Different features have different lengths (i.e. junk regions occupy the majority of the genome).
How to say if my set of intervals - diff methylated regions - is enriched in one of the features? One interval can have intersection with several features. I know how to apply a proportion test, I do not know how to normalise number of intersections between features and intervals for the length of features.