Petersen’s Accident – Incident Causation Theory:
This theory adapts Ferrell’s human factors of overload and also Heinrich’s domino theory and states that causes of accident/incident are human error and/or system failure. Human error is due to overload, traps and decision to err. Human error may directly cause accident or may cause system failure which may cause accident resulting in injury or loss as shown below:
Factors causing overload are much the same in Ferrell’s model.
Traps are due to defective workstation, design and incompatible displays or control.
Decision to err are caused by illogical decision under situation, unconscious desire to err and perceived low probability.
System failure is due to error in policy, responsibility, authority, accountability, measurement, inspection, correction, investigation, orientation, training, selection, safe operating procedure, standards, hazard recognition, records, medical and others.
Suchman stated epidemiological definition of accident as “An unexpected, unavoidable, unintentional act resulting from the interaction of host (accident victim), agent (injury deliverer) and environmental factors within situations which involve risk taking and perception of danger”. His model is shown below.
This originated from the study of epidemics. Casual association between diseases or other biological process (accidents) and specific environment are studies. A classic example of epidemiological method was given by snow who discovered that persons using a particular water supply had a higher death rate from cholera then others. Gordon and McFarland supported that accidental injuries could be studied with the same techniques.
Surry’s Decision Theory:
Jean Surry developed this theory stemming from the epidemiological model of Suchman. It assumes that by a person’s action or inaction, danger occurs to the person. If any negative responses to the question are shown during the danger build-up cycle, the danger becomes imminent, If all replies are positive, the danger diminishes. A negative response to one of the questions will lead to inevitable injury. An accident can be the result of many different routes through the model (20 routes). There are fewer routes leading to no-injury situations.