This paper summarizes the findings of a study of sampling and analytical variance associated with various grades of electrowon copper produced at Noranda's Lakeshore Mine. Production control sampling methods, cathode analyses, variability of precision and accuracy of cathode analysis as a function of cathode quality, and analytical methods are discussed. A general review of customer sampling methods and the effect on settlement assays is included. Also discussed are on-site cathode production analyses and their relationship to wire bar product analyses.