Which diagram is best used to help determine possible root causes of problems?

• A. Bar chart
• B. Gantt chart
• C. Fishbone
• D. Pie chart

Answer: (C)

Root cause analysis is best supported by a diagram that helps you brainstorm and organize every possible factor around a problem. The fishbone diagram does exactly that: you place the problem at the “head” and draw major categories of potential causes as branches off the spine. This layout encourages you to consider different angles—people, processes, equipment, materials, measurements, and the environment—and to group related causes under each category. As you fill in branches, you can spot gaps, connect related issues, and zero in on likely root causes to investigate further.

Bar charts show how often something occurs across categories, which is useful for comparing data but doesn’t map out cause-and-effect relationships. Gantt charts illustrate project timelines and task sequencing, not the origins of a problem. Pie charts display how a whole is divided among parts, which helps with proportions but not with identifying root causes.

So, for tracing and organizing potential root causes, the fishbone diagram is the most effective choice.