WHAT IS 6 SIGMA?
6 Sigma is an improvement methodology developed to reduce variation in processes. Like Lean, Six Sigma is like a toolbox containing many tools. Although a small part of the tools are also used in Lean, it mainly consists of Problem Definition, Problem Solving, Data Analysis and Statistical Methods. Six Sigma is mostly used to solve complex problems of quality. For example, the diameters of some of the bolts produced are not within the desired tolerances, which can be easily solved with the the Six Sigma Method.
WHAT IS VARIATION?
Variation is basically not consistently getting the same results from the output you expect from the process (quality, efficiency, etc.) There are two types of variation in a process: