Six Sigma Training & Certification's Impact on Quality


Six Sigma Training has received considerable attention in the public press. Much of this discussion has been fueled by the huge successes of Six Sigma at Allied Signal, General Electric (GE) and Motorola. These successes have encouraged many other companies to undertake Six Sigma initiatives. Clearly, any application of statistical thinking and methods that produces billions of dollars for major corporations is important, cannot be ignored and is not likely to go away anytime soon.

Clearly there is a lot of interest in Six Sigma Certification. At a first look, one might conclude that Six Sigma Training is nothing new. It uses statistical methods that have been shown to work. It focuses on defect reduction, quality improvement can result and it utilizes project-by-project improvement. One might think that Six Sigma has a short-term focus because projects are completed in 3-6 months. Others say that it is complicated and difficult to understand and just another management fad that “can be ignored and it will go away”. While many of the tools of Six Sigma are not new, the approach and its deployment are unique and the source of its success.


Six Sigma is a business improvement approach that seeks to find and eliminate causes of mistakes or defects in business processes by focusing on outputs that are of critical importance to customers. As a result process performance is enhanced, customer satisfaction is improved and the bottom line is impacted through cost savings and increased revenue. Six Sigma is a strategic approach that works across all processes, products, company functions and industries.

Six Sigma has both management and technical components. On the management side it focuses on getting the right process metrics and goals, the right projects and right people to work on the projects and use of management systems to successfully complete the projects and sustain the gains over time. On the technical side the focus is on enhancing process performance (improving the average level of performance and reducing variation) using process data, statistical thinking and methods, and a disciplined and focused process improvement methodology which has four key stages: measure, analyze. Improve and control. The statistical and other tools (the tools are not all statistical) are linked and sequenced in a unique way that is both easy to use and effective. The approach focuses on the identification of the key process drivers (variables with the largest effects) and relies on software such as Minitab for the statistical calculations.

Six Sigma also provides a process measurement scale. The methodology utilizes “process sigma” as a measure of process capability with a 6-sigma process having a defect level of 3.4 ppm and a 3-sigma process having a defect level of 66,807 ppm. In many instances a 6-sigma process is considered world class. The performance of most processes today is in the 3 to 4-sigma range. The Six Sigma measure of process capability assumes that the process average may shift over the long-term by as much as 1.5 sigma (standard deviations) despite our best efforts to control it. In the case of the 6-sigma process, 3.4ppm is obtained by assuming that the specification limits are 6 standard deviations away from the process target value and that the process may shift as much as 1.5 sigma. The 3.4ppm value is the area under the normal curve beyond 6 – 1.5 = 4.5 sigma. Similarly the 66807ppm for the 3-sigma process is the area beyond 3 – 1.5 = 1.5 sigma.


There are three aspects of Six Sigma that are “new” or at least not properly emphasized by past approaches.

· Integration of the human and process elements of improvement.

· Clear focus on getting bottom-line results ($).

· A method that sequences and links improvement tools into an overall approach.

Many improvement approaches focus on a subset of these elements but none integrate them all, as does the Six Sigma approach.

Six Sigma Training places a clear focus on getting bottom line results. Identification of the business impact is part of the methodology. No Six Sigma project is approved unless the bottom line impact has been identified. Bottom line impact gets the attention of top management for their language is money.

The five phase improvement process; define, measure, analyze, improve, control (DMAIC), sequences and links in a useful way key statistical and other tools that have been found to be effective in improving processes.

These three features together with the other aspects of Six Sigma produce a deployment approach that is better than the deployment approaches used by other quality improvement initiatives. In the past the deployment process for the quality improvement initiative has been the Achilles heel. Failure of improvement initiatives has been typically due to poor deployment

We noted earlier that Six Sigma produces bottom line results (as much as $175,000/project and $1 million/yr). This gets the attention of senior management, who must lead the effort. We believe that these two success factors: bottom line results and active senior management leadership including periodic (weekly, monthly, quarterly) project and program (collection of projects) reviews is what is different about Six Sigma and why it is more successful than other approaches.

Six Sigma Training is also successful because it uses a disciplined, systematic improvement approach, DMAIC, which emphasizes rapid project completion in 3-6 months (sense of urgency). Efforts of longer duration are divided into a series of 3-6 month projects, some of which may be handled in parallel. Success is clearly defined by financial impact and goals for performance metrics such as defects, cycle time, scrap, rework, and capacity. The infrastructure needed for success is clearly specified: senior management leadership, Champions, Master Black Belts, Black Belts, and Green Belts. Six Sigma works because it focuses on improving processes in a way that improves the outputs that are of critical interest of customers and other stakeholders.

The approach is based on the scientific method utilizing statistical thinking and methods. Statistical thinking is fundamental to the approach which focuses on the processes we use to serve our customers, reducing defects by reducing variation, improvement as the goal, and is action oriented.


Quality engineers and statisticians can play a major role in the deployment of Six Sigma. Quality engineers can serve as Black Belts and provide leadership for the teams working on the projects as well as doing the major portion of the project work. Quality engineers will also be called on to be a member of Black Belt teams and provide the quality engineering expertise needed to successfully complete the project. Quality engineers working in organizations not involved in Six Sigma initiatives should work to become skilled in the methodology for it is a very effective approach to process improvement.

Statisticians should also work on problems whose strategic importance or technical complexity is beyond that of the team. Many statisticians in industry have this capability and are performing this role today. They should also take a strategic view, identifying and deploying those statistical methods that are most user-friendly and robust. Like any other work process we want the methods used to be effective when applied by a wide spectrum of people in a wide variety of situations.

As part of their leadership role, statisticians and quality engineers should become visible advocates for Six Sigma and promote the approach and its benefits at every opportunity. The roles of everyone touched by Six Sigma will be different than those experienced in the past. Statisticians and quality engineers can work with management helping them understand, learn, and execute their new responsibilities. This will require that they understand the role of management and the issues they face including the complex demands on managers’ time.


There are several skills required for quality engineers, statisticians and others to be successful in the implementation of Six Sigma. First they should have had considerable experience in applying the statistical tools that Six Sigma uses. There are also a number of non-statistical skills that can help statisticians and others to be successful.

The first requires a change in attitude and focus. Statisticians and other leaders in the Six Sigma environment must be keenly business oriented. They must understand, end-to-end, how the business functions to create value for customers and return a profit to the organization. They must understand the key performance measures, the gaps between current performance and desired performance, the financial stake involved and how to improve processes to get bottom line results. In short, statisticians and quality engineers must be accountable for the success of projects just like the rest of the team members.

Statisticians have always known that to be successful, they have to understand the subject matter (science, engineering, etc.) of the problem they are working on and the needs of the person with which they are working. Six Sigma is no different. The subject matter is business and how its processes function and are improved. The client is management and the managerial processes used to run the organization. Six Sigma brings statisticians into this new field of application (managerial processes) that must be learned and mastered.

In the past, statisticians have solved problems working one-on-one with a client. The problem solving method was informal and typically not written down. This approach worked well because of the small group (2-3 people) and informal nature of communication.

Process improvement using Six Sigma, which often covers two or more organizations and touches the customer, is a different animal. The team is usually larger, 4-6 team members works best but as many as 10 or 12 are often involved. Informal problem solving and improvement methods no longer work in this situation. A common language, roadmap, tools, and sequence and linkage of tools help the team function as a unit with a common thought process. Everyone on the team knows where we are, where we are going, and what steps and activities we are going to conduct to successfully complete the project. “Making it up as we go along” doesn’t work in a team environment.

DFSS relates to how Six Sigma is used in the development of new products and processes. Certainly design of experiments and robustness studies are part of DFSS but there is much more. DFSS is less well developed than Six Sigma for process improvement.

Other areas worthy of investigation are strategies and methods for identifying opportunities for improvement and determining the associated impact on customers and the bottom line. Identification of a “robust” set of improvement tools to be used in conjunction with the DMAIC process is also an important issue.

Finally there is the issue of the infamous 1.5 sigma shift factor in computing process sigma. The development of this factor needs to be more widely understood. If 1.5 is a generic overall number, should I determine the shift factor for my processes and, if so, how should I go about making the determination? Under what circumstances is 1.5 “good enough”?


We must recognize that much personal change is required if we are to make Six Sigma a success. Einstein once said that the definition of insanity is doing the same things and expecting different results. Six Sigma requires statisticians to work in a different way. If fact everyone involved in the Six Sigma initiative must change how they approach improvement. Change is not easy. Hence, organizational change must begin with individuals changing. Certainly those who do not respond to their changing world will have less influence in it.


Six Sigma is different, it works and it can be important to both the success of your organization and your career. Six Sigma is arguably the most important business and industry initiative that has involved statistical thinking and methods. We know of no initiatives involving statistics that has produced returns in the billions of dollars as reported by Motorola, Allied Signal and General Electric. Leadership by senior management as well as much learning and personal change on your part, and that of your colleagues, are required for success.

Six Sigma will last as long as it significantly improves organizational performance including putting dollars on the bottom line. Six Sigma will flourish in those organizations where performance is significantly improved beyond that which can be obtained through other means. If Six Sigma does not produce better business results it will fade away as have other management fads.

Quality Engineers and statisticians can play a role, indeed an important role. Both managerial and technical issues will need to be addressed to be successful. In particular they will need to better understand how the business functions, develop more soft skills including leadership and management skills and deepen our understanding of the job and issues of management and the role of management in Six Sigma initiatives. They will also need to more deeply understand statistical thinking and its associated key elements: process, variation, data, and action. Lots of hard work is required. “Good things don’t come easy”… this is certainly the case for Six Sigma.