NEBOSH Incident Investigation key terms

Any unplanned event, or near miss, that caused or could have caused injury, ill health, damage to property, environmental harm, or a disruption to normal work activity.

An unplanned event that actually resulted in injury, ill health, property damage, or another loss, distinguishing it from a near miss where no loss occurred.

An unplanned event that did not cause injury or damage but had the potential to do so, often revealing the same underlying failures as a serious accident.

The systematic process of gathering and analysing evidence about an incident to establish what happened, why it happened, and what actions will prevent recurrence.

The direct act or condition that produced the incident at the point of contact, such as a slip, a fall, or contact with moving machinery.

The underlying management or organisational failure that, if corrected, would prevent the incident and similar events from happening again.

A structured method such as 5 Whys, fault tree analysis, or Ishikawa diagrams used to trace an incident back to its underlying causal factors.

A simple questioning technique that repeatedly asks why a condition or behaviour occurred, typically five times, to move from symptoms towards underlying causes.

A cause-and-effect diagram, often called a fishbone diagram, that groups possible causes under headings such as people, equipment, materials, methods, measurement, and environment.

A deductive technique that starts with the unwanted top event and works backwards through the combinations of failures and conditions that could produce it.

A diagrammatic risk tool that places the incident at the centre, with threats and preventive barriers on one side and consequences and mitigative barriers on the other.

A behaviour by a person that deviates from a safe procedure or accepted practice and increases the likelihood of an incident occurring.

A physical or organisational state, such as a damaged guard or poor housekeeping, that creates a hazard and contributes to the chance of an incident.

The physical, psychological, and organisational influences on how people perform at work, including fatigue, workload, competence, communication, and interface design.

A contributing influence on an incident arising from what people did or did not do, including decisions, habits, shortcuts, and compliance with rules.

A hidden weakness in management systems, design, or organisation that lies dormant until combined with other factors to cause an incident.

An error or violation committed by a person at the point of work whose effects are felt almost immediately, such as operating a machine without a guard.

A model showing that incidents occur when weaknesses in several layers of protection line up, allowing a hazard to pass through all barriers.

A control, physical or procedural, intended to prevent an unwanted event or to limit its consequences, such as a guard, permit, or alarm.

The ranked order of risk controls from elimination and substitution down to engineering, administrative, and personal protective measures, used to judge the adequacy of corrective actions.

A measure taken to eliminate the cause of a detected nonconformity or incident and prevent it from recurring, ideally addressing root causes rather than symptoms.

The urgent steps taken at the scene to make the situation safe, treat casualties, and preserve evidence before a full investigation begins.

Protecting the incident location, equipment, and physical traces from disturbance or removal so that accurate evidence can be collected later.

Information collected about an incident, including physical items, documents, photographs, witness statements, and measurements, used to establish facts.

A documented record showing who collected, handled, and stored each piece of evidence and when, preserving its integrity for later analysis or legal use.

A written account of what a witness saw, heard, or did, recorded as soon as practicable and in the witness's own words where possible.

A structured conversation with a witness or involved person to obtain factual information about the incident, conducted fairly and without leading the person.

A question beginning with words such as what, how, or describe, which invites a full account rather than a yes or no answer.

A question that suggests the answer the questioner expects, risking contaminated or unreliable evidence and therefore generally avoided in investigations.

A formal document setting out the incident background, findings, causes, conclusions, and recommended actions, written for the audience who must act on it.

A proposed action arising from investigation findings, ideally specific, assigned to a responsible person, and given a realistic completion date.

The UK Reporting of Injuries, Diseases and Dangerous Occurrences Regulations, which require certain serious incidents to be reported to the enforcing authority within set timescales.

An incident of a type and severity that legislation requires to be notified to the relevant authority, such as a specified injury or dangerous occurrence.

The body responsible for regulating health and safety in a workplace, such as the Health and Safety Executive or a local authority in the UK.

A model showing that many minor incidents and near misses occur for each serious injury, so investigating small events can prevent larger ones.

A measure of incidents over a period, usually expressed per 100,000 hours worked or per 1,000 workers, allowing comparison between sites or over time.

Examining incident data over time to identify patterns in type, location, or cause, which can reveal emerging risks that single events do not show.

The knowledge gained from an investigation that is shared across the organisation so that other teams can prevent similar incidents.

The group appointed to conduct an investigation, chosen for relevant technical, operational, and impartial expertise, often including a worker representative.

The written scope of an investigation, defining its purpose, boundaries, team, timescales, and the level of detail required.