What is Six Sigma?

Six Sigma (6) is a process improvement methodology, which aims at reduction in costs & subsequently increases in profits. Its ultimate performance target is virtually defect-free processes and products (3.4 or fewer defective parts per million (ppm)).  Defects may be related to any aspect of customer satisfaction: high product quality, schedule adherence, cost minimization. It describes quantitatively how a process is behaving/performing. A defect is defined as anything outside of customer specifications.
Six Sigma originated at Motorola in the early 1980s and later many companies adopted this approach to improve their process behavior. The Six Sigma methodology consists of the steps "Define - Measure - Analyze - Improve - Control," which is the roadmap to achieve defect free processes. Within this improvement framework, it is the responsibility of the improvement team to identify the process, identify the defect, perform root cause analysis and implement action plans to reduce the defects. In today’s scenario, the companies want to reduce more and more process defects, hence they have started training programs on Six Sigma Certification for their employees internally or the professionals take the training program from certified bodies like ASQ, IASSC, etc. There are different certification belts in a six sigma program-yellow Belt, Green Belt, Black Belt & Master Black belt.
The Six Sigma is a methodology revolves around given below parameters:
        • Everything is a process 
        • All processes have inherent variability 
        • Data is used to understand the variability and drive process improvement decisions 
Six sigma distinguishes itself from other quality improvement programs immediately in the "Define" step. When a specific Six Sigma project is launched, the customer satisfaction goals have been established and decomposed into sub goals such as cycle time reduction, cost reduction, or defect reduction. (This may have been done using the Six Sigma methodology at a business/organizational level.) There are different roles present in the team like six sigma Champion, Sponsor, etc. who help and guide throughout till the completion of the project.
The Define stage for the specific project calls for base lining and benchmarking the process to be improved, decomposing the process into manageable sub-processes, further specifying goals/sub-goals and establishing infrastructure to accomplish the goals. It also includes an assessment of the cultural/organizational change that might be needed for success. The Measure stage consists of capturing and analyzing voice of customer which consists of having a proper data collection plan and mapping the current process. In the Analyze stage, after the data collection has happened, next step is to do analysis and identify the root causes creating the problem. Next stage is Improve stage where most feasible solution is selected amongst the all the probable solution after having numerous brainstorming sessions with the team. In final stage-Control Stage, implementation of solutions takes place with the process being managed and monitored properly. In fact, this is the most important of all the stages as new process needs to be sustained and rolled out as per the plan. If needed, special experiments and modeling may be done to confirm the cause and effect relationships; but many improvement projects may be accomplished with the most basic statistical and non-statistical tools. It is often necessary to iterate through the Measure-Analyze-Improve steps.
Some of the tools used in different stages of the Six Sigma are-:
Define :Contract, Baseline, Kano Model, Quality Function Deployment
Measure:  Sampling Techniques, Data collection, Feedback collection & analysis
Analysis: Cause & Effect Diagrams, FMEA, 5 why’s, Root cause analysis, Statistical Inference.
Improve: Design of Experiments, Robust Design
Control: Statistical Controls & Non statistical Controls
To summarize, six sigma is purely based on statistical logic used to study process behavior by using different statistical tools and correct the process if any deviations are present in the process performance. The primary goal of Six Sigma is to improve customer satisfaction, and thereby profitability, by reducing and eliminating defects.


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