The Six Sigma methodology for problem solving stands for Define, Measure, Analyze, Improve and Control. It is a data-based methodology to define, measure and analyze the problem, to determine the best statistical solutions to solve it and to implement them in the physical process. It designs practical control mechanisms to ensure sustainability. There are two main concepts behind this methodology: “finding causality” is one of them, i.e., solving root causes rather than the symptoms they produce. The other is variability or the obstacles to making, doing, serving or producing always the same (quantities, quality, lead times, cash…).