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Erroneous
Actions: Human Reliability Analysis (HRA). These methods are for analyzing situations in which errors have happened, or might happen. The goal of these techniques is to determine whether human errors will have serious consequences, and to try to identify how likely the errors are to occur. The design of the system or the interface can then be modified to reduce the likelihood of human errors, or mitigate the consequences of them. A current trend in this area is to construct cognitively-oriented models of human error. These techniques are primarily applied in the design of safety critical systems, such as nuclear power plant control rooms.
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Event Tree Analysis:
An event tree is a graphical method for identifying the various possible outcomes of an initiating event. The course of events from the occurrence of the initiating event until is final consequence is determined by the operation or non-operation of various human and physical systems.
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Fault Tree Analysis:
Fault trees show failures that would have to occur to cause an undesired event (an accident). They are constructed as a series of logic gates descending through subsidiary events to basic events at the bottom of the tree. The basic events may be human errors, hardware/software failures, or environmental events.
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Failure Modes and Effects Analysis
(FMEA):
The analyst determines what errors might occur during the execution of a task and their likely consequences for the system.
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Barrier Analysis:
This approach aims to identify hazards that could lead to accidents. For each hazard, any barriers that could prevent the accident are recorded along with their method of functioning and modes of failure (including human error).
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Hazard and Operability Analysis (HAZOP):
An interdisciplinary group is assembled to identify potential hazards, possible consequences, and preventive mechanisms at each step in a process.
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Management Oversight Risk Tree (MORT): A technique used to investigate the adequacy of safety management structures, either to ensure that they exist, or, if an incident has occurred, to determine which safety management functions have failed. In accident investigations, the MORT system firstly defines what barriers have failed, and then searches for the root causes of these failures.
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Work Safety Analysis:
A systematic analysis of a chosen work situation for all possible occupational accidents, plus the measures that may be adopted to reduce or eliminate their likelihood.
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Confusion Matrices:
A tabular plot of a set of stimuli (e.g. displays) against a set of responses is constructed. The frequencies of actual responses are recorded, with the diagonal showing the frequency of correct responses. The grid can be used to identify which responses may be made mistakenly for a given stimulus.
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Operator Action Event Tree:
A representation of success and failure routes through a sequence of actions necessary to perform a task is constructed. Each stage in the route can be given a failure probability resulting in an overall probability of failure or success for the complete event sequence.
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Generic Error Modeling System (GEMS):
An error classification scheme developed by Reason that emphasizes cognitive rather than environmental or context-related factors. GEMS is based on Rasmussen's skills, rules, knowledge (SRK) taxonomy, which describes the competencies needed by workers to perform their roles in complex systems. GEMS describes three major categories of errors: skill-based slips and lapses, rule-based mistakes, and knowledge-based mistakes.
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Cognitive Reliability and Error Analysis
Method (CREAM): A comprehensive approach to HRA that includes a method to conduct an analysis that can be used to both search for the causes of errors and predict performance, an error classification scheme that consists of a number of groups that describe person-related, technology-related, and organization-related errors, and an underlying model of operator cognition called COCOM (Contextual Control Model) that describes how actions are chosen based on the result of the interaction between competence and context.
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