Complete firstObserved problem
Event and deviation are described verifiably.
During an active failure, first arrange necessary containment and evidence preservation.
Method guideOperations
Root Cause Tree Analysis
A practical method guide: clarify prerequisites and materials, understand the complete process, and look up outputs, pitfalls, and stop criteria.
ComplexityMedium
Time1-3 h
Participants2-8
FormatWorkshop
MaturityEstablished
01
Prerequisite
What needs to be finished first
02
Preparation
What needs to be ready before start
Materials
Timeline, logs, tree workspace, evidence register and action list.
People / roles
Process experts, affected operators, data experts and independent facilitator.
Pre-read
Specify problem, period and deviation from expectation; preserve timeline, logs and affected people as sources.
Time needed
60–120 minutes initial tree; evidence checks separately
Setup
Place the event at the top; branch causal hypotheses below with IDs and evidence status beside each branch.
03
Core question
The one question this method answers
Which evidenced conditions explain the problem and which can we usefully change?
04
Flow
Phases with goal, actions, output and pitfall
A cause tree decomposes an observed problem into possible contributing conditions and checks each branch against evidence. This is a general cause-tree analysis, not a proprietary diagnostic system or a decision-selection tree.
Root Cause Tree Analysis· worksheet
Fictional example
A cause tree decomposes an observed problem into possible contributing conditions and checks each branch against evidence. This is a general cause-tree analysis, not a proprietary diagnostic system or a decision-selection tree.
Top event
Which concrete deviation is being explained?
Fictional: 12 course registrations received no confirmation within ten minutes on Tuesday.
Tree and links
Record direct conditions, subcauses and joint prerequisites with IDs.
E0 missing confirmation ← H1 sending fails OR H2 message is discarded. H1 ← H1a token expired AND H1b sending uses that token. H1a ← H1a1 expiry reached AND H1a2 no timely renewal.
Evidence status
Which source supports or rejects each branch?
Fictional logs confirm expiry and use of the old token. Stored queue entries reject H2. The operating plan lacks a renewal process, supporting H1a2.
Actions and review
What corrects the event and what prevents recurrence?
Renew token and resend twelve confirmations in a controlled way. Jan adds expiry alerting and renewal ownership; simulate the next expiry in a test.
All example details are fictional and illustrate the application.
- 1
Problem
Problem
Goal
Problem definition
Inputs for this step
- Event data
- Expected state
Actions
- Record expected state, actual state, period and extent.
- Reconstruct the event sequence with sources and mark conjectures separately.
Output
Problem definition
Is the problem separate from its assumed cause?
Quality check
Is the problem separate from its assumed cause?
Pitfall
The problem is labelled poor staff. State an observable deviation without blame.
Timing: 10–20 minutes
- 2
Causal branches
Causal branches
Goal
Hypothesis tree
Inputs for this step
- Problem
- Timeline and expertise
Actions
- Branch possible direct conditions and ask how they arose.
- Allow multiple contributing causes; explicitly mark joint prerequisites.
Output
Hypothesis tree
Does each branch explain a causal mechanism?
Quality check
Does each branch explain a causal mechanism?
Pitfall
A single why-chain excludes alternatives. Add alternative branches and contributing conditions.
Timing: 20–30 minutes
- 3
Branch review
Check branches
Goal
Reviewed cause tree
Inputs for this step
- Hypothesis tree
- Evidence sources
Actions
- Check each causal claim using logs, documents, observations or a targeted test.
- Record supported, rejected or open status with counterevidence and next check.
Output
Reviewed cause tree
Are open hypotheses visibly unresolved?
Quality check
Are open hypotheses visibly unresolved?
Pitfall
A frequent assumption becomes fact without evidence. Require evidence and do not declare an unconfirmed branch a root cause.
Timing: 20–45 minutes
- 4
Actions
Countermeasures
Goal
Action with impact review
Inputs for this step
- Reviewed tree
- Agency
Actions
- Act on confirmed influenceable conditions and distinguish prevention from immediate correction.
- Agree owner, date and later effectiveness evidence; keep open branches active.
Output
Action with impact review
Does the action change an evidenced condition?
Quality check
Does the action change an evidenced condition?
Pitfall
A reminder replaces fixing a missing barrier. Examine concrete technical or process safeguards.
Timing: 15–25 minutes
05
Artifact
What comes out at the end
Sketch: what the artifact looks like
Form
Cause tree with supported, rejected and open branches plus actions on confirmed influenceable conditions.
Versioning / ownership
Record date and scope; retain the previous version and reason when changing it.
Tool alternatives
- Cause-tree whiteboard
- Versioned diagram
- Evidence register with source links
root-cause-tree-analysis-working-template.md
Specify problem, period and deviation from expectation; preserve timeline, logs and affected people as sources.
Root Cause Tree Analysis: Worksheet
Question
To be confirmed
Desired outcome
To be confirmed
Scope
Complete cycle Time: 60–120 minutes initial tree; evidence checks separately
Complete this worksheet on paper or in your own document during the work.
Preparation for this scope
Method setup
- Materials: Timeline, logs, tree workspace, evidence register and action list.
- Roles: Process experts, affected operators, data experts and independent facilitator.
- Advance information: Specify problem, period and deviation from expectation; preserve timeline, logs and affected people as sources.
- Overall time needed: 60–120 minutes initial tree; evidence checks separately
- Setup: Place the event at the top; branch causal hypotheses below with IDs and evidence status beside each branch.
Prepare for the work steps
Problem: Problem
- Event data
- Expected state
Causal branches: Causal branches
- Problem
- Timeline and expertise
Branch review: Check branches
- Hypothesis tree
- Evidence sources
Actions: Countermeasures
- Reviewed tree
- Agency
Root Cause Tree Analysis· worksheet
Top event
Which concrete deviation is being explained?
...
Tree and links
Record direct conditions, subcauses and joint prerequisites with IDs.
...
Evidence status
Which source supports or rejects each branch?
...
Actions and review
What corrects the event and what prevents recurrence?
...
Answer the prompts with your own information. Explicitly mark unknowns and assumptions.
US Department of Energy: Root Cause Analysis Guidance
Problem: Problem
Expected artifact: Problem definition
Is the problem separate from its assumed cause?
Entry:
...
- Is the problem separate from its assumed cause?
Causal branches: Causal branches
Expected artifact: Hypothesis tree
Does each branch explain a causal mechanism?
Entry:
...
- Does each branch explain a causal mechanism?
Branch review: Check branches
Expected artifact: Reviewed cause tree
Are open hypotheses visibly unresolved?
Entry:
...
- Are open hypotheses visibly unresolved?
Actions: Countermeasures
Expected artifact: Action with impact review
Does the action change an evidenced condition?
Entry:
...
- Does the action change an evidenced condition?
Open questions and next steps
...
Method guide: https://methodatlas.meierhoff-systems.de/en/methods/root-cause-tree-analysis/run-sheet
06
Example output
Concrete filled scenario, fictional example
Fictional example for orientation. Counts and timings describe this case and are not universal requirements.
root-cause-tree-analysis-beispiel.md
Concrete filled scenario, fictional example
Fictional example
Top event: Fictional: 12 course registrations received no confirmation within ten minutes on Tuesday.
Tree and links: E0 missing confirmation ← H1 sending fails OR H2 message is discarded. H1 ← H1a token expired AND H1b sending uses that token. H1a ← H1a1 expiry reached AND H1a2 no timely renewal.
Evidence status: Fictional logs confirm expiry and use of the old token. Stored queue entries reject H2. The operating plan lacks a renewal process, supporting H1a2.
Actions and review: Renew token and resend twelve confirmations in a controlled way. Jan adds expiry alerting and renewal ownership; simulate the next expiry in a test.
07
Pitfalls
Recognize symptoms and steer against them
Quick overview, the full text is in the matching phase in the flow
- ProblemThe problem is labelled poor staff.View in phase
- Causal branchesA single why-chain excludes alternatives.View in phase
- Check branchesA frequent assumption becomes fact without evidence.View in phase
- CountermeasuresA reminder replaces fixing a missing barrier.View in phase
Trap
Problem
Symptom
The problem is labelled poor staff.
What to do
State an observable deviation without blame.
Trap
Causal branches
Symptom
A single why-chain excludes alternatives.
What to do
Add alternative branches and contributing conditions.
Trap
Check branches
Symptom
A frequent assumption becomes fact without evidence.
What to do
Require evidence and do not declare an unconfirmed branch a root cause.
Trap
Countermeasures
Symptom
A reminder replaces fixing a missing barrier.
What to do
Examine concrete technical or process safeguards.
08
Stop criteria
When to pause, resolve prerequisites, or choose another approach
If human error ends the tree, investigate conditions, barriers and information further; do not use personal judgements as causes.
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