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Six‐Sigma: methodology, tools and its future

Yahia Zare Mehrjerdi (Department of Industrial Engineering, Yazd University, Yazd, Iran)

Assembly Automation

ISSN: 0144-5154

Article publication date: 22 February 2011




This paper aims to introduce some of the most important and fundamental points about Six‐Sigma and the main points that researchers, implementers and users should keep in mind in addressing Six‐Sigma to large and small companies as well as system development and/or planning for such applications. In addition to that this author proposes an algorithm for calculating the overall sigma level of a multistage system. Example problems are provided and the weighting technique is discussed.


The paper provides a general review of the Six‐Sigma and some of its extensions. The topic is followed by the introduction of a new algorithm that can be used for calculating the overall sigma level of a multistage system.


In a journey to business excellence, an organization is successful if specific goals for critical processes of the organization are identified. The quality management programs implemented can modernize and simplify activities towards the ultimate goal of the business. Regarding that, the author discusses key issues as such as leadership commitment, what Six‐Sigma would bring to the organization, how it works, Six‐Sigma business strategies, Six‐Sigma methodologies, mathematical formulation of Six‐Sigma, the use of simulation with Six‐Sigma, new Six‐Sigma, benefits of Six‐Sigma, costs of Six‐Sigma, critical success factors and the future of Six‐Sigma.

Practical implications

Six‐Sigma has the potential to change the quality program of an organization. When the selected quality program is Six‐Sigma, the organizational goal is to reach a sigma level of 6, or the objective of 3.4 defects per million opportunities.


In this paper, the author reviews the fundamental concept of Six‐Sigma and elaborates why it is important for small and large organizations to employ Six‐Sigma concepts into their working methodology for quality improvement. The DMAIC steps to be taken, tools to be used and the deliverables are completely discussed. The author also discusses a Six‐Sigma weighted average methodology for calculating the overall Six‐Sigma level for an organization with many working stages or processes.



Zare Mehrjerdi, Y. (2011), "Six‐Sigma: methodology, tools and its future", Assembly Automation, Vol. 31 No. 1, pp. 79-88.



Emerald Group Publishing Limited

Copyright © 2011, Emerald Group Publishing Limited

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