Six Sigma is a disciplined, data-driven methodology used to improve processes by eliminating defects. A defect is defined as any non-conformance of a product or service to its specifications. The core principle of Six Sigma is to reduce process variation to the point where there are no more than 3.4 defects per million opportunities (DPMO). It achieves this by using a structured framework, such as DMAIC (Define, Measure, Analyze, Improve, Control), and statistical methods to identify and remove the root causes of defects and minimize variability in manufacturing and business processes, thereby improving the quality of the output.

1. Pyzdek

T.

& Keller

P. A. (2014). The Six Sigma Handbook (4th ed.). McGraw-Hill Education. In Chapter 1

"What Is Six Sigma?"

it is defined as a methodology that "is a rigorous

focused

and highly effective implementation of proven quality principles and techniques... aimed at virtually eliminating defects from every product

process

and transaction" (p. 5).

2. Antony

J.

& Banuelas

R. (2002). Key ingredients for the effective implementation of Six Sigma program. Measuring Business Excellence

6(4)

20-27. The authors state

"Six Sigma is a business strategy and a systematic methodology to improve... process performance

and to enhance customer satisfaction by reducing the number of defects" (p. 20). https://doi.org/10.1108/13683040210451679

3. De Feo

J. A.

& Juran

J. M. (2010). Juran's Quality Handbook: The Complete Guide to Performance Excellence (6th ed.). McGraw-Hill. Chapter 22

"Six Sigma and Other Improvement Methodologies

" describes Six Sigma as a "business improvement approach that seeks to find and eliminate causes of defects and errors in manufacturing and service processes by focusing on outputs that are critical to customers" (p. 587).

4. MIT OpenCourseWare. (2004). 16.853 Advanced System Design and Management I. Lecture 5: Quality and Process Control. The lecture notes define Six Sigma as a "disciplined

data-driven approach and methodology for eliminating defects" and notes its goal is to reduce variability and defects to a level of 3.4 DPMO (Slides 12-14).