How do you link your CTQ tree to your DMAIC phases and tools in Lean Six Sigma?

1 Define phase

The first step in any Lean Six Sigma project is to define the problem, the goal, the scope, and the team. This is where you use your CTQ tree to identify the key customer needs and expectations that your process must meet or exceed. You can use tools such as surveys, interviews, focus groups, or Kano analysis to collect the VOC and then organize it into categories or themes. Then, you can create a CTQ tree by asking "what does this mean?" or "how do we measure this?" for each category or theme until you reach the level of measurable CTQs. For example, if your customer says they want fast delivery, you can ask "what does fast mean?" and "how do we measure fast?" to define the CTQs such as delivery time, delivery frequency, or delivery accuracy.

2 Measure phase

The next step is to measure the current performance of your process and establish a baseline for your CTQs. This is where you use your CTQ tree to select the appropriate data sources, methods, and tools to collect and analyze the data. You can use tools such as data collection plans, check sheets, histograms, control charts, or Pareto charts to measure the variation, capability, and defects of your process. You can also use tools such as process maps, SIPOC diagrams, or value stream maps to understand the flow, inputs, outputs, and wastes of your process. By using your CTQ tree, you can ensure that you are measuring what matters to your customer and that you have valid and reliable data.

3 Analyze phase

The third step is to analyze the root causes of the problem and identify the factors that affect your CTQs. This is where you use your CTQ tree to narrow down the potential causes and test the hypotheses. You can use tools such as fishbone diagrams, 5 whys, brainstorming, or affinity diagrams to generate and organize the possible causes. Then, you can use tools such as scatter plots, regression analysis, hypothesis testing, or design of experiments to verify the relationship and significance of the causes and the CTQs. By using your CTQ tree, you can focus on the most critical and influential factors and avoid wasting time and resources on irrelevant or trivial ones.

4 Improve phase

The fourth step is to improve your process by implementing solutions that address the root causes and enhance your CTQs. This is where you use your CTQ tree to evaluate and prioritize the potential solutions and plan the implementation. You can use tools such as solution selection matrix, cost-benefit analysis, risk analysis, or FMEA to compare and rank the alternatives based on their impact, feasibility, cost, and risk. Then, you can use tools such as action plans, pilot tests, or PDSA cycles to execute and monitor the changes. By using your CTQ tree, you can align your solutions with your customer needs and expectations and ensure that they are effective and sustainable.

5 Control phase

The final step is to control your process by standardizing the improvements and preventing the recurrence of the problem. This is where you use your CTQ tree to establish and communicate the new process standards and performance indicators. You can use tools such as control plans, SOPs, work instructions, or training materials to document and disseminate the best practices and procedures. You can also use tools such as control charts, dashboards, or audits to track and review the performance of your CTQs and identify any deviations or opportunities for further improvement. By using your CTQ tree, you can maintain and improve your customer satisfaction and loyalty and ensure the continuity and consistency of your process.