Sorry for the confusion..i performed differential expression by giving 15 samples as individual input to edgeR and it gave me a file name Filename.normalized.FPKM and it has values ranging from 0 to 800,000 . I think its not a fold change. so, how can i get some meaningful data out of two groups or is there a way where i can do differential expression diffently by combining in to two groups?


I share @Rm's confusion. You said you already did differential expression with edgeR -- so what are you trying to do again? If you're interested in differential expression, keep your data in a "count matrix" and w/ a proper design matrix and forget the FPKM values for now.