 thumb|200px|the common six sigma symbol  six sigma is a set of techniques and tools for process improvement. it was developed by motorola in 1986. jack welch made it central to his business strategy at general electric in 1995. today, it is used in many industrial sectors. six sigma seeks to improve the quality of process outputs by identifying and removing the causes of defects (errors) and minimizing variability in manufacturing and business processes. it uses a set of quality management methods, including statistical methods, and creates a special infrastructure of people within the organization ("champions", "black belts", "green belts", "yellow belts", etc.) who are experts in these methods. each six sigma project carried out within an organization follows a defined sequence of steps and has quantified value targets, for example: reduce process cycle time, reduce pollution, reduce costs, increase customer satisfaction, and increase profits. the term six sigma originated from terminology associated with manufacturing, specifically terms associated with statistical modeling of manufacturing processes. the maturity of a manufacturing process can be described by a sigma rating indicating its yield or the percentage of defect-free products it creates. a six sigma process is one in which 99.99966% of the products manufactured are statistically expected to be free of defects (3.4 defective parts/million), although, as discussed below, this defect level corresponds to only a 4.5 sigma level. motorola set a goal of "six sigma" for all of its manufacturing operations, and this goal became a by-word for the management and engineering practices used to achieve it. ==doctrine== six sigma doctrine asserts that: * continuous efforts to achieve stable and predictable process results (i.e., reduce process variation) are of vital importance to business success. * manufacturing and business processes have characteristics that can b
1986_introductions Business_terms Evaluation_methods Process_management Production_and_manufacturing Quality Six_Sigma