This book covers how to measure the performance of operators quickly and simply, how to identify the most efficient operators, and how to monitor their improvement over time. The method described can be automated very easily, thereby requiring no labor consumption. The approach is grounded in one of the basic laws of factory physics: mastery of variability. Despite its successful application in the automotive industry, it should be underscored that this method is only a tool that should be used in the broader framework of Standardized Work deployment.