Teams use cause-and-effect diagrams to visualize, clarify, link, identify, and classify possible causes of problems in processes, products, and services. They are also referred to as “fishbone diagrams,” “why-why diagrams,” or “Ishikawa diagrams” (after Kaoru Ishikawa, a quality expert from Japan).
Through understanding problems within the work processes, teams can identify root causes of a problem. A diagnostic approach for complex problems, this technique begins breaking down root causes into manageable pieces of a process. A cause-and-effect diagram visualizes results of brainstorming and affinity grouping through major causes of a process problem. Through a series of “why-why” questions on causes, this process can uncover the lowest-level root cause. Figure 5-6 displays a sample cause-and-effect diagram.
Cause-and-effect diagrams are applicable for:
· Analyzing problems
· Identifying potential process improvements
· Identifying sources of defect causes
· Analyzing improper use of test routines/testing problems
· Scheduling problems/cycle times