Pros and cons of Six Sigma: an academic perspective

by Jiju Antony on 7th January 2008

Introduction

Six Sigma is a business strategy that seeks to identify and eliminate causes of errors or defects or failures in business processes by focusing on outputs that are critical to customers (Snee, 1999). It is also a measure of quality that strives for near elimination of defects using the application of statistical methods. A defect is defined as anything which could lead to customer dissatisfaction. The fundamental objective of the Six Sigma methodology is the implementation of a measurement-based strategy that focuses on process improvement and variation reduction.

A number of papers and books have been published showing the fundamentals of Six Sigma, a list of which can be found at the end of this white paper. I personally have experienced that senior management in many organisations view Six Sigma as another quality improvement initiative or flavour of the month in their list.

I am often told by many engineers and managers, in small and big companies, that there is nothing really new in Six Sigma compared to other quality initiatives we have witnessed in the past. In response, I often ask a simple question to people in organisations who practise TQM, “what do you understand by the term TQM?” I often get many varying answers to this question. However if I ask a bunch of Six Sigma practitioners, “what do you know of the term Six Sigma?”, I often get an answer which means more or less the same thing and concurs with what I would have expected. The following aspects of the Six Sigma strategy are not accentuated in previous quality improvement initiatives:

Six Sigma strategy places a clear focus on achieving measurable and quantifiable financial returns to the bottom-line of an organisation. No Six Sigma project is approved unless the bottom-line impact has been clearly identified and defined.
Six Sigma strategy places an unprecedented importance on strong and passionate leadership and the support required for its successful deployment.
Six Sigma methodology of problem solving integrates the human elements (culture change, customer focus, belt system infrastructure, etc.) and process elements (process management, statistical analysis of process data, measurement system analysis, etc.) of improvement.
Six Sigma methodology utilises the tools and techniques for fixing problems in business processes in a sequential and disciplined fashion. Each tool and technique within the Six Sigma methodology has a role to play and when, where, why and how these tools or techniques should be applied is the difference between success and failure of a Six Sigma project.
Six Sigma creates an infrastructure of champions, master black belts (MBBs), black belts (BBs) and green belts (GBs) that lead, deploy and implement the approach.
Six Sigma emphasises the importance of data and decision making based on facts and data rather than assumptions and hunches! Six Sigma forces people to put measurements in place. Measurement must be considered as a part of the culture change.
Six Sigma utilises the concept of statistical thinking and encourages the application of well-proven statistical tools and techniques for defect reduction through process variability reduction methods (e.g. statistical process control and design of experiments).

Just like any other quality improvement initiatives we have seen in the past, Six Sigma has its own limitations. The following are some of the limitations of Six Sigma which create opportunities for future research: