Fishbone diagram

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assess

First Added:June 22, 2026

Fishbone diagram (Ishikawa or cause-and-effect diagram) maps a problem at the “head” and sorts possible causes into branching categories along the spine. We assess it because it structures postmortem brainstorming when several factors may contribute, but it needs facilitation and a follow-up drill-down. It belongs under Technique with Incident Management and SRE learning practices. Use it when a failure has multiple plausible branches, then run Five Whys on each rib.

Blurb

A fishbone diagram is a quality tool that helps users identify the many possible causes for a problem by sorting ideas into useful categories.

Summary

Fishbone diagrams shine when a problem has multiple contributing dimensions and a single Five Whys chain would miss parallel causes. The problem sits at the head; category ribs collect candidate causes; sub-causes branch off each rib.

Step	Action
1	Write the problem statement as an agreed fact
2	Pick 4-6 categories the team understands
3	Brainstorm causes on each rib without debating fixes yet
4	Run Five Whys on the highest-signal branches
5	Convert roots into process, guardrail, or automation action items

Diagram format: Classic fishbone on a whiteboard works in the room. For docs in Git, Mermaid mindmaps are often easier to maintain than beta fishbone syntax. Same shape: root = problem, branches = cause paths.

Sibling technique: First Principles applies when designing forward from constraints, not when mapping an incident backward.

Details

Common Category Sets

Pick labels the team already uses. Rename freely; clarity beats jargon.

Set	Categories
6Ms (manufacturing)	Manpower, Machine, Method, Material, Measurement, Mother Nature (environment)
4Ss (service)	Surroundings, Suppliers, Systems, Skills
Ops/postmortem	People, Process, Tooling, Environment, Measurement

Mermaid Options

Format	Status	Best for
`ishikawa-beta`	Beta in Mermaid	Fishbone-shaped diagrams in docs
`mindmap`	Stable	Version-controlled cause trees; easier day-to-day editing

Here is the example in both formats on the same “Blurry Photo” problem.

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ishikawa-beta
    Blurry Photo
    Process
        Out of focus
        Shutter speed too slow
        Protective film not removed
        Beautification filter applied
    User
        Shaky hands
    Equipment
        LENS
            Inappropriate lens
            Damaged lens
            Dirty lens
        SENSOR
            Damaged sensor
            Dirty sensor
    Environment
        Subject moved too quickly
        Too dark

mindmap
    root((Blurry Photo))
        Process
            Out of focus
            Shutter speed too slow
            Protective film not removed
            Beautification filter applied
        User
            Shaky hands
        Equipment
            LENS
                Inappropriate lens
                Damaged lens
                Dirty lens
            SENSOR
                Damaged sensor
                Dirty sensor
        Environment
            Subject moved too quickly
            Too dark

Integration with Five Whys

Fishbone answers where to look. Five Whys answers how deep to dig on each branch. Do not stop at the fishbone brainstorm; shallow ribs produce shallow fixes.