Templates & Examples / Project Templates

Cause-and-Effect (Fishbone) Diagram

A structured framework to systematically map and categorise the root causes of a failure before attempting to design solutions.

8 min read 4 Sections Quality Assurance

In this resource

Understanding the Framework
Standard Categorisation Methods
Worked Example: Website Performance
Implementation Guide

§1 Understanding the Framework

Developed by Kaoru Ishikawa, the Cause-and-Effect diagram forces teams out of immediate, often flawed, conclusion-jumping.

When a complex problem occurs, human nature frequently dictates fixing the most obvious symptom. The Fishbone diagram counteracts this by providing a visual map that branches out into categorical domains, guiding a team to explore all underlying contributors. The "head" of the fish represents the problem or effect, while the "bones" extending from the central spine represent the diverse categories of potential causes.

This templated approach guarantees that investigations do not stall in isolated silos. By providing exactly six entry vectors, analysts map environmental constraints next to technological hurdles, creating an unbiased, holistic view of the failure landscape.

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§2 Standard Categorisation Methods

While the six branches can be entirely custom, they are most frequently populated using established industry mnemonics. Select the grouping that closest matches your sector:

Manufacturing (The 6Ms)

Machine, Method, Material, Manpower, Measurement, and Mother Nature (Environment). Highly suited for physical production environments and hardware engineering.

Service Industries (The 6Ps)

People, Process, Policy, Plant (Technology/Facilities), Program, and Product. Customarily utilised in software delivery, consulting, and administrative processes.

KEVOS® Principle: Never force an issue into a category if it doesn’t fit cleanly. Customising the branches (e.g., swapping out "Measurement" for "Tools" in IT environments) is a valid and often necessary adaptation of the framework.

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§3 Worked Example: Website Performance

A breakdown from a real-world digital agency post-mortem outlining compounding issues.

Consider a scenario from Mary’s Consulting, where a newly deployed company website experienced severe performance degradation. The defined effect was quantifiable: Site performance fell below the LCP < 2.5s target on image-heavy pages. Instead of merely blaming the server size, the team broke down the contributing elements using a tailored set of categories.

Category	Identified Root Causes
People	Limited frontend performance optimisation experience within the delivery team.
Technology	Excessively heavy JavaScript bundle; inefficient CMS rendering layers; absence of code splitting.
Tools	No performance checks configured on Pull Requests (PRs); absence of a Content Delivery Network (CDN) for static assets.
Process	Performance testing was isolated to the very end of the cycle; no enforced performance budgets during the build.
Materials / Content	Too many distinct font weights loaded simultaneously; vast, unoptimised imagery uploaded by content editors.
Environment	User latency magnified by mobile 4G network conditions; staging/production connected to a slow hosting tier.

By visualising this spread, the team identified that the solution required a combination of upskilling (People), infrastructure changes (Tools/Environment), and stricter build pipelines (Process/Technology), rather than applying a single patch.

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§4 Implementation Guide

To deploy this framework effectively in your next retrospective or incident analysis, follow these four chronological phases:

Define the Effect clearly. Draw the head of the fish. Write the problem statement. It must be specific, quantified where possible, and agreed upon by the entire group.
Establish the Categories. Draw the spine and the six angled lines. Choose between the 6Ms, 6Ps, or a custom blend (e.g., People, Technology, Tools, Process, Materials, Environment).
Populate the Causes. Conduct a brainstorming session. For every symptom or hurdle raised, categorise it onto the appropriate branch.
Ask "Why?". For every cause attached to a branch, interrogate it with the Five Whys technique to ensure you have reached the systemic root, rather than a surface-level symptom.

1. Target Precision

Vague effects yield vague causes. Always use numerical thresholds (like LCP < 2.5s) to ground the analysis.

2. Team Diversity

Never populate a diagram in a vacuum. Bring in varied disciplines to avoid missing vital categories like Environment or Process.

3. Next Steps

A diagram solves nothing on its own. Translate identified root causes into a Pareto chart to prioritise the immediate corrective actions.

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Handbook application: from concept to controlled practice

Purpose. This expanded section turns the original page into a practical handbook. It preserves the supplied material and adds a repeatable way to apply, check and review Cause-and-Effect (Fishbone) Diagram. It does not replace a contract, legislation, a controlled standard, competent engineering judgement or specialist advice.

The operating aim is to make the blank artefact usable by explaining what belongs in each field, who supplies it and how it is reviewed. Read the original explanation first, then use the workflow and checks below to convert knowledge into evidence.

Use Cause-and-Effect (Fishbone) Diagram as a decision instrument rather than an administrative form. The subject terms—fishbone, diagram, framework, root, problem—need an explicit connection to the project objective, business value and stakeholder commitments. Before completing the artefact, write one sentence stating who will use it, what decision it supports and when that decision is required.

Apply a disciplined information model. Separate facts supported by evidence, forecasts derived from a method, assumptions awaiting validation, constraints that limit choice, risks that may occur, issues that already exist and actions assigned to people. Each material entry should have an owner, date, status and next review point. Where probability or impact scores are used, define the scale so different reviewers interpret it consistently.

A baseline is useful only when changes are visible. Give the artefact an identifier, version, approval state and effective date. Define which changes require reapproval, how superseded versions are retained and where supporting evidence is stored. During reviews, focus on exceptions, decisions and trends rather than reading every field aloud. Record the decision and rationale, not merely that a meeting occurred.

Close the loop beyond delivery. Confirm acceptance criteria, unresolved items, transferred responsibilities and operational ownership. Where benefits are expected, identify the outcome measure, baseline, target, observation period and owner who remains accountable after the project team disbands. Lessons should describe the condition, consequence and reusable action; a generic statement such as “communicate better” cannot improve the next project.

Step-by-step operating method

Name the decision. Write the decision, approval, handover or control activity the completed template must support.
Assign ownership. Nominate one accountable owner and identify contributors, reviewers and approvers.
Gather evidence. Use records, estimates, stakeholder input and source references rather than unsupported opinion.
Complete with discipline. Use consistent dates, units, identifiers, status values and version controls.
Review and maintain. Check completeness and logic, approve the baseline, then update it when trigger conditions occur.

Completion and governance protocol

Start with a short drafting workshop involving the accountable owner and the people who hold the evidence. Complete high-consequence fields first: objective, scope, owner, baseline, acceptance, dependencies and escalation. Mark unknowns as assumptions or actions rather than hiding them behind vague prose. Circulate a review draft, resolve conflicting interpretations, baseline the approved version and place the next review date in an owned schedule.

Information type	Minimum useful content	Review test
Outcome	Observable change and intended recipient	Not merely a deliverable or activity
Measure	Definition, baseline, target, frequency and source	Two reviewers would calculate it the same way
Ownership	One accountable role plus contributors and approver	Authority matches responsibility
Uncertainty	Assumption, risk or issue with response and trigger	Status reflects current reality
Control	Version, approval, review date and change rule	Current baseline is identifiable

Common failure modes and recovery actions

1. Watch for

Filling every box even when a field is not applicable instead of recording why.

Recovery: Return to the governing definition or requirement and restate the decision in one sentence.

2. Watch for

Writing vague statements without an owner, measure, date or evidence source.

Recovery: Separate evidence from assumption, assign an owner and set a date for validation.

3. Watch for

Copying a previous project without revalidating assumptions and stakeholders.

Recovery: Run a small counterexample, boundary test, pilot or independent check before proceeding.

4. Watch for

Using the document as a private worksheet when it is meant to support a shared decision.

Recovery: Record the consequence, decision and rationale, then update the controlled baseline.

5. Watch for

Creating an approved baseline but failing to define who maintains it and when.

Recovery: Escalate when the issue affects safety, compliance, acceptance, material value or an agreed tolerance.

Review checklist

Is the purpose and intended decision clear to a reader outside the team?
Are owners, dates, measures and sources complete and internally consistent?
Which fields are assumptions and how will they be validated?
What event, threshold or review date causes this document to change?
Are mandatory requirements distinguished from recommendations and illustrative values?
Are sources, assumptions, units, dates and versions recorded closely enough to reproduce the decision?
Have safety, legal, ethical, stakeholder and operational consequences been considered at the appropriate level?
Is there a named owner and a trigger for review, escalation, change or retirement?

Questions for deeper application

What is the most important distinction a practitioner must preserve when applying Cause-and-Effect (Fishbone) Diagram?