Which of the following is a model used to understand how and why incidents happen?

• A. Three Levels of Incident Causation Model
• B. Why Method
• C. OSHA's problem-solving techniques
• D. Fault Tree Analysis

Answer: (A)

A structured, multi-layer framework for tracing why an incident happened. This model looks at causes at three levels: the immediate factors that directly led to the event (things like unsafe acts or unsafe conditions), the contributing factors that make those immediate causes more likely (such as supervision, training gaps, or equipment maintenance issues), and the root/systemic factors that shape the overall safety environment (organizational policies, safety culture, resource priorities). By organizing causes this way, investigators can move beyond blaming individuals and reveal how management systems, practices, and culture created the conditions for the incident.

The Why Method is a helpful technique for probing causes by repeatedly asking why, but it’s a questioning approach rather than a full model you apply to the whole incident. Fault Tree Analysis is a formal analytical method that maps how combinations of events lead to a top-level failure, but it’s a specific diagrammatic technique focused on logic of failures rather than describing a broad, layered understanding of incident causation. OSHA’s problem-solving techniques are general guidelines for addressing issues, not a dedicated model for explaining how and why incidents occur.