Event Tree Analysis (ETA) in Power BI
A Power BI event tree visual that branches an initiating event through every function that responds to it, success above and failure below, out to each outcome. Add branch probabilities and an initiating frequency when you want to quantify it, and each sequence's path probability and frequency are written on its outcome, next to its identifier.
Part of Ataytis Assurance, with all six analysis modes in one visual. 30-day free trial, licensed and billed through Microsoft Marketplace.
The arithmetic, when you need it
Add branch probabilities and each sequence's path probability is written on its outcome. Add an initiating frequency and it becomes a sequence frequency.
Sequences named for you
Identifiers such as IE-S1-F2, built from each branch taken, so every outcome can be referenced.
Splits that add up
Branch probabilities from 0 to 1, and the branches of every split adding up to 1, checked as you build.
About the method
What is event tree analysis?
Event tree analysis (ETA) is a forward-looking method that starts from an initiating event and follows the success or failure of each safeguard, system or action that responds to it, out to every possible outcome. It can be used qualitatively, to lay out what can follow, or quantitatively: with a frequency for the initiating event and a probability for each branch, it shows how often each outcome can be expected. It is also one of the risk assessment techniques in IEC 31010:2019.
Also known as
- ETA
- Event tree
- Event tree diagram
Common uses include
- Consequence analysis
- Quantitative risk assessment
- Process safety
- Incident and accident analysis
- Emergency response planning
- Business continuity
Event tree analysis can be used wherever the outcome of an event depends on whether the safeguards and responses that follow it work.
From a table to an event tree
Each row names a node and the node before it, with an optional probability for the branch that leads there. The tree is laid out left to right, and once probabilities and an initiating frequency are in, every outcome is quantified. Add a Diagram ID and one table holds several event trees, with a slicer or the diagram picker switching between them.
Click a node for everything behind it
Select an outcome or a pivotal event and the Node Inspector opens beside the tree with whatever your table holds for it, such as its status, path, branch and path probabilities, sequence frequency, owner or severity. You choose which columns appear and what each heading is called, and the rest of the report filters to that node.
Follow one sequence through a review
Choose Focus branch on any node, and its path back to the initiating event and every branch after it stay prominent while the rest of the tree fades. It makes it easy to review one outcome and the sequence of successes and failures that led to it.
Your data
Ten rows, five quantified sequences
A loss of containment: gas detection, then ignition, then fire suppression on the path where gas was detected. The tree draws without Probability and Frequency; add them in Values, set to Don't summarize, and every sequence is quantified.
| Node ID | Connected Node ID | Node Type | Label | Relationship Type | Probability | Frequency | Order |
|---|---|---|---|---|---|---|---|
| IE | Initiating Event | Loss of containment | 0.026 | 1 | |||
| DET | IE | Pivotal Event | Gas detected? | Next | 2 | ||
| IGN-A | DET | Pivotal Event | Ignition avoided? | Success Branch | 0.98 | 3 | |
| IGN-B | DET | Pivotal Event | Ignition avoided? | Failure Branch | 0.02 | 4 | |
| OUT-1 | IGN-A | Success Outcome | Contained, no ignition | Success Branch | 0.92 | 5 | |
| SUP | IGN-A | Pivotal Event | Fire suppressed? | Failure Branch | 0.08 | 6 | |
| OUT-2 | SUP | Consequence | Controlled fire | Success Branch | 0.97 | 7 | |
| OUT-3 | SUP | Consequence | Escalated fire | Failure Branch | 0.03 | 8 | |
| OUT-4 | IGN-B | Consequence | Unignited release | Success Branch | 0.92 | 9 | |
| OUT-5 | IGN-B | Consequence | Escalated fire | Failure Branch | 0.08 | 10 |
What it writes on the outcomes
Controlled fire, for example, is 0.026 × 0.98 × 0.08 × 0.97, in the same units as the initiating frequency.
| Outcome | Shown on the outcome |
|---|---|
| Contained, no ignition | IE-S1-S1 · f = 2.34e-2 |
| Controlled fire | IE-S1-F2-S1 · f = 1.98e-3 |
| Escalated fire (OUT-3) | IE-S1-F2-F2 · f = 6.12e-5 |
| Unignited release | IE-F2-S1 · f = 4.78e-4 |
| Escalated fire (OUT-5) | IE-F2-F2 · f = 4.16e-5 |
What it draws
Every node and branch
Drawn in a Custom look by default, with a profile designed with reference to IEC 62502:2010, Analysis techniques for dependability – Event tree analysis (ETA), one setting away.
Nodes
- Initiating event
- Pivotal event
- Branch point
- Success outcome
- Failure outcome
- Consequence
Branches
- Success branch
- Failure branch
- Conditional branch
- Sequence
Worked out
- Sequence identifier
- Path probability
- Sequence frequency
Validation
Checked against the rules of the method as you build
The Validation tab lists anything that breaks these rules and where it is, so the diagram is right before it reaches a review.
- Exactly one initiating event, with nothing leading to it
- Every pivotal event and branch point has branches
- Nothing follows an outcome
- Branch probabilities from 0 to 1
- The branches of every split add up to 1
- An initiating frequency of 0 or more
- Every branch of a split has a probability, or none does
- No cycles
Getting started
From your table to event trees in a report
Install from Marketplace
In Power BI Desktop, open Get more visuals, search for Ataytis Assurance, and add it.
Add your table
Put Node ID, Connected Node ID, Node Type and Relationship Type in Data fields, and Probability and Frequency in Values when you want the sequences quantified.
Choose Event Tree Analysis
Select the visual, open More options (…) and choose Edit, then pick Event Tree Analysis in the Diagram type list on the left.
Licence it to publish
Power BI Desktop needs no licence. Readers in the Power BI Service do, with the first 30 days free.
Pricing
One licence includes all six analysis modes
Event Tree Analysis is included alongside Fault Tree Analysis, Bow-Tie Risk Analysis, Reliability Block Diagram, Goal Structuring Notation and Markov State Diagram. Ataytis Assurance is licensed per user: $4.99 per user per month for small teams, dropping to $2.49 for 500 users or more. The first month is free on every plan, billed by Microsoft.
Licensing a large team or a whole organisation? Request an enterprise quote
Also in Ataytis Assurance
The other analysis modes in the same visual
Every licence includes all six. Switch mode in the editor, and each one keeps its own mapping, layout and look.
Fault Tree Analysis
How could this top event happen?
Explore fault treesBow-Tie Risk Analysis
What can go wrong, what prevents it, and what limits the consequences?
Explore bow-tiesReliability Block Diagram
Does the system keep working when parts of it fail?
Explore reliability block diagramsGoal Structuring Notation
Does the argument for a claim hold together?
Explore goal structuresMarkov State Diagram
How does a system move between states over time?
Explore Markov diagramsQuestions
Event Tree Analysis questions
Your next event tree, in Power BI
Build it in Power BI Desktop with no licence and nothing to sign up for. A licence only comes into it when the report is published for others to open.