Supreecha, the formulas for Cg and Cgk are in question, to me. The Formulas shown are multiplying 6*s and 3*s, but are in fact dividing 6/s and 3/s. Other documents are showing multiplication. There are not a lot of documents out there but the ones I have seen are using multiplecation. What bothers me is that the MiniTab comparison is giving the same answers. Please advise?