Six Sigma improves the capability of the business process and reduces cost, saves time and increases revenue through qualitative and quantitative techniques. The qualitative and quantitative techniques involve a data-driven approach. Since Six Sigma involves a data-driven approach, it is supported through a well-implemented metrics program.
Six Sigma includes two methodologies DMAIC and DMADV to improve the process that is deviated from the target line or falls below the specification limit. These methodologies are inspired by Deming’s plan PDCA (Plan-Do-Check-Act). These methodologies include five stages – DMADV – Define, Measure, Analyze, Design and Verify and DMAIC – Define, Measure, Analyze, Improve and Control. The process of DMADV methodology in Six Sigma is used to develop a new processes or products at Six Sigma quality levels. Six Sigma emphases the DMAIC approach to solve the problems through defining, measuring, analyzing, improving and controlling the process. DMAIC model was initially developed for helping manufacturing industries but DMAIC process is flexible enough to be applied in other industries hence the benefits was extended to other industries such as health care system, educational systems, financial service.
DMAIC vs. DMADV
DMAIC (Define, Measure, Analyze, Improve, Control) and DMADV (Define, Measure, Analyze, Design, Verify) are widely used the statistical tool in Six Sigma methodologies. DMAIC defines the business process and DMADV redefines the process to meet the customer requirement.
- DMADV approach is used to redesign the process however DMAIC focus on controlling and improving the process.
- DMADV measures customer specification and needs but DMAIC measures the current performance of a process.
- DMADV suggests a business model meet the customer requirement but DMAIC monitors the current performance and improvement of a process.
DMAIC process interconnected with five phases – Define, Measure, Analysis, Improve and Control phases improves, optimizes, and stabilizes the business improvement. It focuses on improving the current business process or solves the current business problem through a data-driven quality strategy. DMAIC approach includes corporate champions, business unit managers, and business unit champions to identify the opportunities that are linked to customer needs.
Define Phase – Defines the problem, opportunities, goals and customer requirements. It focuses on selecting high-impact project through focusing on CTQ (Critical to Quality) The deliverable of the define phase will be the project charter that includes the project objective, goal, team members, cost benefit.
Measure Phase – Measures the process performance and documents the current process and validates the baseline performance. Measurement system analysis in the measure phase depends upon the type of data been collected. For instance; for variable data – Gage R& R, Attribute data – Attribute agreement analysis tools are preferred. SIPOC, Process mapping, top down charting can be commonly used for both types of data to explain the process flow.
Analyze Phase – Determines root causes of variation and isolates the top causes behind the CTQ. In most cases, the root cause may exceed more than three. A tool such as Pareto Chart helps to prioritize the top causes. Most commonly used tools to identify the root causes are 5- Why, Fish-bone diagram. Tools to validate the cause are Scatter Diagram, Regression Analysis, and Hypothesis Testing.
Improve Phase – Fully understands the root causes and eliminates the top causes. Tools used to prioritize the solution are Affinity Diagram, Solution prioritization matrix. Tools to validate the solutions are Hypothesis Testing, Regression analysis
Control Phase – Improves process and monitors future process performance. This phase involves error-proof the process and creates a checklist to sustain the changes made in the improve phase. Tools used in this phase include Standard Operating Procedure, Automation, and Checklist.