Pros and Cons of Six Sigma

The following aspects of the Six Sigma strategy are not accentuated in previous quality improvement initiatives.

1) 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.

2) Six Sigma strategy places an unprecedented importance on strong and passionate leadership and the support required for its successful deployment

3) 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.

4) 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.

5) 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.

6) 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.

7) 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)

The following are some of the limitations of Six Sigma which creates opportunities for future research.

1) The challenge of having quality data available, especially in processes where no data is available to begin with (sometimes this task could take the largest proportion of the project time)

2) The right selection and prioritisation of projects is one of the critical success factors of a Six Sigma program. The priorit isation of projects in many organisations is still based on pure subjective judgement. Very few powerful tools are available for prioritising projects and this should be the major thrust for research in the future.

3) The statistical definition of Six Sigma is 3.4 defects or failures per million opportunities. In service processes, a defect may be defined as anything which does not meet customer needs or expectations. It would be illogical to assume that all defects are equally bad when we calculate the Sigma Capability level of a process. For instance, a defect in a hospital could be a wrong admission procedure,misdiagnosis, lack of training required by a staff member,misbehaviour of staff members, unwillingness to help patients when they have specific queries, etc.

4) Assumption of 1.5 sigma shift for all business processes does not make much sense. This particular issue should be dealt with extra caution as a small shift in sigma could lead to erroneous defect calculations.

5) Non-standardisation procedures in the certification process of Black belts, Green belts, etc. Research has shown that the skills and expertise developed by Black belts/Green belts are inconsistent across companies and are dependent a great deal on the certification body. Black belts believe they know all the practical aspects of advanced quality improvement methods such as Design of Experiments, Robust Design, Response Surface Methodology, Statistical Process Control and Reliability, when in fact they have  barely scratched the surface.

6) Six Sigma can easily digress into a bureaucratic exercise if the focus is on such things as the number of trained Black Belts and Green Belts, number of projects completed, etc. instead of bottomline savings.

7)There is an overselling of Six Sigma by too many consulting firms. Many of them claim expertise in Six Sigma when they barely understand the tools and techniques and the Six Sigma roadmap.

8) The relationship between Cost of Poor Quality (COPQ) and Process Sigma Quality Level requires more justification.