Six Sigma approach is a methodology, an improvement and management strategy in which easy and effective statistical tools are used to define, measure, analyze, improve and control selected processes in businesses in order to ensure excellence in operations.

It is an approach that aims to reach a near-perfect level based on the improvement of business processes in order to continuously increase business performance and customer satisfaction level. It facilitates the elimination of errors by finding the causes in production and service processes. It also focuses on increasing efficiency and meeting customer expectations better by reducing the cost and cycle times of processes. Six Sigma approach , measurement as a means of ” Million Error Number ” (Defects per Million Opportunities) uses the scale.

The ultimate goal of Six Sigma is to make money for the business. How much gain will be made in the improvements to be made in Six Sigma projects and its return are definitely questioned.

Although errors that are not even 1% are very rare, this is unacceptable for some businesses and in some situations. For example, 0.27% of the planes failing in the air means that hundreds of planes crash in one day. Considering that a mother holds her baby in her arms 100 times a day, a mother who hugs her child with this error rate will drop her baby every 4-5 days.

Historical Development

The six sigma approach started in the 1970s when the American Motorola company sold its television company Quasar to a Japanese company, Matsushita, due to low efficiency, and significantly reduced the error rates there thanks to the effective changes Matsushita made in the factory. Intrigued by the secret of this Japanese success, Motorola experts determined that it was a matter of process quality , and in the early 1980s they began fighting for performance improvement at Motorola.

Motorola first started using Six Sigma techniques in its internal training, in hopes of improving and improving the quality of cellular phones. With this method, Motorola was able to measure its flaws in all business sectors, and in 1988 it achieved all its goals using the Six Sigma methodology. With this success, it became the first company to receive the Malcolm Baldridge national quality award.

At the end of 1995, General Electric started to implement Six Sigma in the company with all support and leadership systems. In 1997, the company spent 400 million dollars on six sigma-related training, and a return of 600 million dollars was obtained as a result of Six Sigma’s applications.

After Motorola and General Electric, IBM was one of the companies that implemented the Six Sigma methodology. He achieved significant success with the Six Sigma approach at IBM. Afterwards, the Six Sigma approach, which became widespread in the automotive industry, can be applied in almost every sector today.

Application of Six Sigma Approach

There are different management approaches and different methods used in order to realize improvements in businesses. In fact, most of the improvement methods used are based on W.Edwards Deming’s PDCA – Plan, Do, Check, Act- cycle. The Six Sigma approach, on the other hand, works like a technical staff. The DMAIC  approach , which is a similar approach to PUKO and comes from the initials of the words Define, Measure, Analyze, Improvement and Control in English, is followed.


Identifying ( D ef a)

The Six Sigma approach, called DMAIC, is the first step of the improvement plan , the identification phase, to identify the potential problem and determine the impact of this problem on customer satisfaction, stakeholders, employees and profitability. At this stage, critical customer requests, project goals and objectives, roles and responsibilities of the team, process map
and performance criteria etc. is defined. It is aimed to define the outputs and potential inputs for each process, together with the determination of the objectives, limits and deadlines of the project.

  • Project Management System and Project Planning
  • Project Indicators
  • Voice of the Customer
  • Detailed Process Chart
  • Failure Mode Effect Analysis (FMEA)
  • Cause-Effect Matrix

Measurements ( M easur A)

During the measurement phase, the project status report is filled and the deadlines and targets are determined. Then, the project team is selected and care is taken to include representatives from the process, suppliers and customers in this team. While drawing the flowchart of the process, the inputs and outputs are determined. A list of the outputs and inputs of the process that creates the problem is prepared, and cause-effect relationships are examined using tools such as cause-effect diagram, cause-effect matrix and error mode and effects analysis (FMEA).

At this stage, the main purpose is to make sure that the inputs and outputs of the project are correct and to reveal the current situation with the help of different visual analyzes. Studies to determine how accurately process performance indicators are measured or not are carried out at this stage. It is tested whether the output and potential inputs are measured correctly. After having a correct measurement system, the adequacy of the current outputs and inputs is determined.

  • Scoreboard Diagram
  • Pareto Chart
  • Graphical Analysis
  • Process Sigma
  • Descriptive Statistics
  • Z-estimates

Analysis ( A analysis)

In the analysis phase, analyzes are made to identify methods to eliminate the gap between the current performance of the problem or process and the desired goal. At this stage, statistical data analyzes are used to help understand the data. Using questions such as where, when, how, and how, potential inputs that may affect outputs are analyzed. In this way, the order of importance, error severity, etc. issues can be clarified.

  • Multivariate Analysis
  • correlation
  • Hypothesis tests
  • confidence intervals
  • T-test
  • F-test
  • Chi-square Test

Improvement ( I mprovement)

In the improvement phase, solutions are designed to eliminate the problems of the process and implementation plans are developed. The continuity of improvement is ensured by including the necessary people in the improvement system through in-service training and motivation systems.

  • Multiple Regression
  • Creativity
  • Data collecting
  • Flow Diagrams
  • Experiment Design
  • Hypothesis Testing

Control (Control)

Keeping outputs there is just as important as optimizing them. Checking that the identified important inputs continue in their chosen state will reduce the variability on the output. In the control phase, if the process improvement is successful, it is verified and it is ensured that the improvement will continue over time.

The action to be taken; to eliminate human-based mistakes, to provide up-to-date training, to update control procedures, to eliminate the special causes of change and to ensure that the new process is under statistical process control. When the new process is stable, actual business results are documented. If the targets are not met, the DMAIC cycle is restarted as a corrective action.

  • Statistical Process Control
  • Reliability
  • Tolerance Analysis
  • Documentation and Standardization
  • Evaluation of Results
  • Control Chart

In the implementation of the Six Sigma approach, first of all, the right projects should be determined for the strategic and critical success factors of the business, and a team of people who will take part in these projects should be selected.

Critical Success Factors in Six Sigma

Six Sigma projects are planned activities that act within a certain system and are carried out within the framework of certain rules. Although the application levels and their effects on project success differ according to the sector, we can list the generally accepted Critical Success Factors as follows.

  • Management Participation and Commitment
  • education
  • Organizational Infrastructure
  • Cultural Exchange
  • Linking Six Sigma to Business Strategy
  • Linking Six Sigma to Human Resources
  • Linking Six Sigma to Customers
  • Linking Six Sigma with Suppliers
  • Communication

Benefits of the Six Sigma Approach

Today, many companies share their Six Sigma approach successes on their websites. When these shares are examined, it is seen that the Six Sigma methodology is beneficial especially in the following areas.

  • Providing performance target for employees
  • Reduction in cycle time
  • Reduction in costs
  • Increase in customer satisfaction
  • Increase in product quality
  • Decreased margin of error
  • Increasing market share
  • Reduction of product costs
  • Leap improvements
  • Positive cultural change
  • speaking the common language

You can tell us your opinions and questions about the six sigma approach as comments.

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