Task analysis technique assessment system

The goal of human error quantification is to produce error probabilities, building on task analysis and error identification techniques to provide a probabilistic risk assessment (PRA). This provides numerical estimates of error likelihood and of the probability of overall likelihood of system breakdown. Quantification of error is the most difficult aspect of HRA, often heavily reliant on expert judgement, rather than the more rigorous approach of actual observation and recording of error frequencies. Such techniques are little used in healthcare but have been successfully applied to anaesthesia (Pate-Cornell and Bea, 1992). Nevertheless, some hospital tasks, such as blood transfusion, are highly structured and the quantification of errors probabilities would seem to be eminently feasible (Lyons et al, 2004). 

Techniques for the identification and evaluation of human error are typically labeled Human Reliability Assessments (HRA). A complete HRA starts with a definition of the problem and development of a task analysis to support the HRA (Kirwan, 2005). The core of HRA is the Human Error Identification (HEI) and Human Error Quantification (HEQ) stages, and several methods have been developed to specifically focus on these two areas. From these, control measures can be identified to reduce the overall system risk. 

The O SHA is an analysis technique for identifying hazards in system operational tasks. The O SHA is an analysis technique for specifically assessing the safety of operations by integrally evaluating operational procedures, the... 

The assembly process (Figure 10-1) brings together all of the assessment tasks to provide the risk, its significance, how it was found, its sensitivity to uncertainties, confidence limits, and how it may be reduced by system improvements. Not all PSAs use fault trees and event trees. This is especially true of chemical PSAs that may rely on HAZOP or FMEA/FMECAs. Nevertheless the objectives are the same accident identification, analysis and evaluation. Figure 10-1 assumes fault tree and event tree techniques which should be replaced by the equivalent methods that are used. 

CTA is a bottom-up technique used broadly to analyse the relationships between system hazards (identified by the System Hazard Assessment in Figure 7) and operational tasks and the HMI design. The analysis works in a bottom-up fashion from operational tasks, related to base events, to identified service-level hazards. 

Human error reliability assessment technique. Detailed analysis of the functions to be accomplished by the human/machine/ environment system and the tasks performed by the human to achieve those functions. 

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