ive noticed significant discrepancies even on the same cut of jean from the same designer. i try on 10 pair of diesels of the same size at the store before deciding which one i want. im somewhere between a 28 and 29 in their zathan or zaf, so it takes me a while to find the right fit. each pair is unique, i guess. but i think between brands the discrepancy is more of where the designer descides to make his measurement. the rise varies a great deal, so i dont think its even possible to standardize the measurement of the waist on jeans.