Six sigma is a data driven, customer focused, and result oriented methodology which uses statistical tools and techniques to systematically eliminate the defects and inefficiencies to improve processes. It is a systematic method to measure and analyze the business processes to identify critical factors affecting business results, thereby improving the processes and establishing controls around the improved processes.
Six sigma is a widely accepted quality concept in the corporate world today. Six Sigma started its journey in the 1980s as a data driven method to reduce variation in electronic manufacturing processes in Motorola Inc. in the USA. Six Sigma became famous when Jack Welch made it vital to his successful business strategy at General Electric in 1995. Today it is used as a business performance improvement methodology all over the world in diverse industry including general manufacturing, construction, banking and finance, healthcare, education, government, KPO/BPO, IT/Software. At present IT/ ITES sector companies are dynamically implementing Six Sigma and it is no more confined into manufacturing sector.
The term ‘six sigma’ comes from statistics and is used in statistical quality control (SQC) which evaluates process capability i.e. the numerical measure of the ability of a process to meet the customer specifications. It was originated from terminology associated with manufacturing which refers the ability of manufacturing process to produce a very high proportion of output within specifications. The sigma rating of a process indicates its yield or percentage of defect-free outputs it produces. A six sigma process is the one which produces 99.99966% statistically defect-free outputs which is equivalent to 3.4 defects per million opportunities (DPMO).
Six sigma uses a set of quality management and statistical methods and creates a team of experts within the organisation (Executive Leadership, Champions, Black belt, Green Belt, Yellow Belt etc.) having specific skill sets required to carry out the six sigma project. Each six sigma project carried out within an organisation follows a defined sequence of phases with quantifiable value targets e.g. reduction in process cycle time, reduce cost, increase in quality rating/ customer satisfaction index, reduction is defect rate.
Road Map of a Six Sigma project:
- Identify the areas of improvement
- Define the problem statement and goals for improvement in quantifiable terms (i.e. which can be measured numerically)
- Determine the resources required for the project
- Formulate a project deliverables timeline in a phased manner
- Establish performance parameters/ metrics
- Gather baseline information about the process
- Validate measurement system for the process output (Y)
- Examine the data collected in the earlier phase to determine a prioritized list of sources variation
- Explore potential causes (potential X’s for causation) and determine the impact of each X has on the response Y
- Determine the optimum level of vital few X’s
- Validate measurement system for X’s
- Verify process improvement
- Develop control mechanism to ensure sustenance of the improved process
Some of benefits of Six Sigma are given below:
- Six Sigma helps companies to reduce cost and improve productivity
- Six Sigma improves quality of projects output by reduction of inefficiencies and defects
- Six Sigma increases customer satisfaction, and loyalty
- Certified Six Sigma Professionals can help increasing ROI significantly
Six Sigma Methodologies
There are mainly two methodologies of Six Sigma namely DMAIC and DMADV.
DMAIC is a data-driven Six Sigma methodology for improving existing products and processes. The DMAIC process should be used when an existing product or process can be improved to meet or exceed the customer’s requirements. DMAIC methodology consists of five phases: D – Define, M – Measure, A – Analyze, I – Improve, C – Control.
- Define – Define the project targets and customer (internal and external) deliverables.
- Measure – Measure the process to determine the current process performance (baseline).
- Analyze – Find out the root causes of the defects.
- Improve – Improve the process by eliminating defects.
- Control – Control the future performance.
DMADV is a common DFSS (Design for Six Sigma) methodology used to develop a process or product which does not exist in the company. DFSS is an application of Six Sigma which focuses on the design or redesigns of the different processes used in product manufacturing or service delivery by taking into account the customer needs and expectations. DMADV is used when the existing product or process does not meet the level of customer specification or Six Sigma level even after optimization with or without using DMAIC. DMAIC methodology consists of five phases: D – Define, M – Measure, A – Analyze, D – Design, V – Validate.
- DEFINE the project goals and customer deliverables
- MEASURE the process to determine the current performance level
- ANALYZE and determine the root causes of the defects
- DESIGN the process in detail to meet customer needs
- VALIDATE the design performance and its ability to meet the customer needs
Refer details about specific Program
Six Sigma Yellow Belt (SSYB)
Six Sigma Green Belt (SSGB)
Six Sigma Black Belt (SSBB)
Lean Six Sigma Black Belt (LSSBB)
Six Sigma versus Traditional Quality
|Six Sigma||Traditional Quality|
|Decisions are driven by data||Decisions are taken based on a combination of data and ‘gut feel’.|
|Control process inputs (Focus on X’s)||Inspection method (Focus on Y)|
|Structured use of statistical tools to help in problem solving||No formal structure exists for the application of tools|
|Structured training in applied statistics||Lack of structured training|
|Root cause approach||Band aid approach|
|Prevention over inspection||Inspection over prevention|
Six Sigma Characteristics
- Customer centric
- Process focused
- Data driven
- Involvement and support of the top management
- Cultural change
- Breakthrough performance gains
- Structured improvement deployment
- Validation through key business results
- Reduction in variation
- Elimination of defects
- Improvement in yield
- Enhancement in customer satisfaction
- Strengthening of the bottom line