Hi all, I met an error when I use splicing.index with by.chip=T. > si.em_nv_bychip <- splicing.index(x=x.rma, genes=sig.genes, group="cell_type", members=c("EM", "NV"), by.chip=T) Error in function (classes, fdef, mtable) : unable to find an inherited method for function "rowttests", for signature "matrix", "character" Appreciate any kind help. Thanks. Xin