Swiss cheese model
The Swiss Cheese Model (English Swiss cheese model) is a pictorial representation of latent and active human failure as a contribution to the collapse of complex systems and describes the concatenation of causes of accidents. The model was originally set out by the British psychologist James Reason of Manchester University and has since found wide acceptance.
The Swiss cheese model compares security levels with consecutive slices of cheese. The holes in the cheese, such as Emmentaler are an image for the imperfection of safety or protection measures in a security system. The cheese holes and vulnerabilities can unexpectedly change their size and location. With an unfavorable combination of many causal factors, individual error to damages, accidents or catastrophic consequences develop. In the model, then the cheese holes lie on a line and there is the " opportunity of a trajectory ," says Reason, which overcomes all the security barriers. Instead of a model of Swiss cheese can also be regarded as a useful metaphor.
Latent and active fault
Reason investigated the accident reports of disasters such as Bhopal, Challenger, King's Cross, Chernobyl and Zeebrugge and suggested a distinction between active and latent failures; later he speaks of people and system errors. Reason represents the hypothesis that most accidents can be traced to one or more of four error sectors: organizational influences, supervision, preconditions and concrete actions. Deferred error of the system had been created long before an adverse event on the management and organizational level, before they led to the accident along with unfavorable conditions and unsafe acts by individuals ( active failure).
Application
The Swiss cheese model of accident causation is used in the risk analysis and risk management. It is the starting point for the planning of security among others in engineering and healthcare, rail and aviation. For system security, it is applied in the industrial and organizational psychology.
In daily life, errors that happen in a model cheese hole, but can be stopped with a functioning system of the next slice of cheese as a safety barrier occur.
On the basis of the Swiss - cheese model Critical Incident Reporting systems were ( German reporting systems on critical incidents ) for notification of critical events (English critical incident ) and Beinahvorfällen (English near miss ).
Reasons frog described model with mathematical concepts as a model in the percolation theory, which he analyzed as a Bethe lattice.
Error: person or system
When an adverse event accusations (English frontline ) are mostly against the actors in " front line" collected. However, the observation of damage or accident may take place by Reason in two ways: people or system error.
Uncertainty springing from the ranks of management or supervision, for example, when inexperienced pilots are put together for a night flight into known adverse weather conditions as occupation. Organizational influences manifest themselves in such cases by spending cuts in pilot training in times of tight budgets.
The same basic structure is also applied in health care. Due to a typographical error on the prescription a doctor prescribed a harmful dose. This can be regarded as careless of the doctor, as it arises about lack of time. More than a quarter of their working time using German Doctors for bureaucracy in health care.
Details of the active failure are often difficult to predict. However, it can be identified latent preconditions before an adverse event occurs (see emergence), the more " principle in view of existing personnel and operational risks to make systems more robust" - and not primarily avoiding errors, but the result of defense as an approach of the security system.
Theories and models of accident causation
In understanding the causes of accidents to Reason is bordered on the years employed persons approach. In theories with a people approach the unsafe acts or omissions of persons are considered mainly - as a result of " forgetfulness, inattention, poor motivation, carelessness, negligence and recklessness ". Human errors are classified as moral problem: " bad people bad things happen ," referred to by psychologists as just- world fallacy ( German fallacy of a just world ).
The theory of " symptoms versus causes" suggests instead that pay particular attention to the obvious, leading to the accident error to judge, should be studied with his reasons at the root; for unsafe acts and unsafe conditions are merely symptoms. " Symptoms versus causes" is viewed more as a warning rather than a theory in the study of the causes of accidents.
As the first model of accident causation, the Domino model of Herbert William Heinrich ( 1931) has been described. Here, the accident with a row of dominos is compared. Once a stone falls, it will upset all the others. It represents a complete sequence of factors, with the last stone corresponds to the accident itself. Thus, a simple cause / effect principle is described. The model should not be confused with the domino effect.
In addition to the Domino and Swiss cheese model found other models little attention. Criticism of the Swiss - cheese model is rare.