Once the head and spine are drawn, the team needs a way to organize its ideas. Categories give people prompts so the brainstorm does not stall after the first few suggestions.
Key Concept
Categories exist to trigger ideas, not to limit them. The classic manufacturing set is the 6Ms: Manpower (people), Machine, Method, Material, Measurement, and Mother Nature (environment). Service, healthcare, and office teams often build their own set, such as People, Policies, Procedures, and Technology. Measurement is the easiest category to forget, yet a worn gauge or an unclear inspection rule can make a healthy process look broken.
Practical Example
A clinic wants to understand why patients often wait more than 40 minutes. The team skips the 6Ms and chooses Scheduling, Staffing, Facilities, and Patient Flow. Under Scheduling someone adds "every appointment is booked for 10 minutes, even long consultations," and under Patient Flow "paperwork is collected only after patients sit down."
Lesson Summary
- ✓Choose categories that fit the problem instead of forcing the problem into a fixed set.
- ✓During brainstorming, collect ideas without judging them; save the debate for later.
- ✓Stay on causes while building the diagram, because jumping to solutions too early shuts down the search.
- ✓Repeated "why" questions push the team past symptoms toward causes that can actually be fixed.