Table of Contents
Introduction
Choosing the right methods for incident investigation is crucial for identifying root causes and preventing future workplace incidents. This article explores popular investigation methods, their applications, and how they contribute to a safer work environment.

Why Incident Investigation Methods Matter
Different incidents require different approaches to uncover their root causes. Effective methods:
- Provide structure and clarity.
- Help identify immediate and systemic issues.
- Enable organizations to implement targeted corrective actions.
Top Incident Investigation Methods
1. The 5 Whys
- Description: A simple technique that involves asking “Why?” repeatedly until the root cause is identified.
- Steps:
- Define the problem.
- Ask why the problem occurred.
- Continue asking why for each subsequent answer until the root cause is reached.
- Best For: Straightforward incidents with a single cause.
- Example:
- Problem: Machine malfunctioned.
- Why? The motor overheated.
- Why? Lack of cooling.
- Why? The cooling fan was not maintained.
- Root Cause: Poor maintenance schedule.
2. Fishbone Diagram (Ishikawa Diagram)
- Description: A visual tool that categorizes potential causes of a problem into key areas.
- Steps:
- Define the effect (problem) at the “head” of the diagram.
- Identify major cause categories, such as People, Process, Equipment, and Environment.
- Brainstorm potential causes within each category.
- Best For: Complex incidents with multiple contributing factors.
- Example: A diagram showing how training gaps, faulty equipment, and poor procedures contribute to workplace accidents.
3. Fault Tree Analysis (FTA)
- Description: A graphical method that maps the sequence of events leading to an incident.
- Steps:
- Start with the incident at the top of the tree.
- Identify all events and conditions that could lead to the incident.
- Use “AND” and “OR” gates to show relationships between contributing factors.
- Best For: Analyzing high-risk scenarios with multiple interdependent causes.
4. Bowtie Analysis
- Description: A diagrammatic approach that connects causes to consequences via preventive and reactive controls.
- Steps:
- Identify the hazard and top event (incident).
- Map out causes leading to the incident on the left side of the “bowtie.”
- Map out consequences on the right side.
- Add barriers to prevent causes and mitigate consequences.
- Best For: Risk management and visualizing controls.
5. Event and Causal Factor Analysis (ECFA)
- Description: A timeline-based method that traces events and decisions leading to an incident.
- Steps:
- Create a timeline of the incident.
- Identify actions, decisions, and conditions at each point.
- Highlight where failures or deviations occurred.
- Best For: Investigating incidents with a clear sequence of events.
How to Choose the Right Method
Consider the following factors when selecting an investigation method:
- Complexity of the Incident: Use simple tools like the 5 Whys for straightforward incidents and advanced techniques like FTA for complex ones.
- Available Resources: Some methods require more time, expertise, or tools.
- Purpose of Investigation: Ensure the method aligns with the investigation’s goals, such as identifying systemic issues or improving risk controls.
Best Practices for Using Investigation Methods
- Train Investigators: Provide training on multiple methods to match different scenarios.
- Engage Teams: Involve employees, supervisors, and safety professionals for diverse insights.
- Document Findings: Maintain clear records of the analysis process and results.
- Combine Methods: Use multiple methods for a comprehensive analysis when needed.
Conclusion
Incident investigation methods are essential tools for uncovering root causes and enhancing workplace safety. By selecting the appropriate method and following best practices, organizations can ensure thorough investigations and effective corrective actions. Stay tuned for the next article, where we discuss the importance of defining incidents in workplace safety.
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