In one of the example in SLqPCRdata package stated below, I am unsure in the last line i.e. exprData <- normPCR(SLqPCRdata, c(3,4)), whether SLqPCRdata should have been relData ? According to the help page of normPCR, it requires a data.frame containing relative quantities. SLqPCRdata contains the average take-off values, but relData contains relative expression values for realtime quantitative RT-PCR data based on take-off values. data(SLqPCRdata) relData <- apply(SLqPCRdata, 2, relQuantPCR) geneStabM(relData[,c(3,4)]) exprData <- normPCR(SLqPCRdata, c(3,4)) > sessionInfo() R version 2.8.1 (2008-12-22) i386-pc-mingw32 locale: LC_COLLATE=English_United States.1252;LC_CTYPE=English_United States.1252;LC_MONETARY=English_United States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] SLqPCR_1.8.0 RColorBrewer_1.0-2