Root-cause analysis: one effect, causes grouped by category, the confirmed cause highlighted.
1 fishbone diagram example
Checkout conversion root cause
Five categories of causes investigated for a twelve percent drop in checkout conversion.
A fishbone shows what was investigated, not just the conclusion. Each bone is a category with its sub-causes, and exactly one bone, the confirmed root cause in the data layer, shares the accent with the effect box.
A fishbone diagram, also called an Ishikawa or cause-and-effect diagram, organizes the possible causes of a problem. Kaoru Ishikawa developed it for quality management in Japan. The effect sits at the head and causes branch off the spine by category.
Read it from the head backwards. Each major bone is a category, classically the 6 Ms (methods, machines, materials, manpower, measurement, environment), and the smaller bones are specific causes within it.
When to use a fishbone diagram
Use it in a root-cause workshop, for example after checkout conversion drops, to list every plausible cause before jumping to a fix.
Use it to show which cause was confirmed by data and which were ruled out.
If you already know the cause and need to plan the fix, use a flowchart or action plan instead.
How to make a good fishbone diagram
State the effect as a specific, measurable problem, such as "Checkout conversion fell 18% in May".
Choose categories that fit your domain; software teams often use code, infrastructure, data, people and process.
Write causes as concrete facts, not vague labels like "communication".
Highlight the confirmed root cause so the diagram records the conclusion, not only the brainstorm.
