Task analysis evaluation

TALENT Task Analysis Linked EvaluatioN Technique NUREG/CR-5534, 1991... 

The HRA evaluates errors that may affect the probabilities of system success and failure but do not appear in ihc task analysis. Some of these can he disregarded by assuming that a certain condition does or does not exist. For example, for a post-inamienance losi. the concern is for... 

Human Factors Engineering/Ergonomics approach (control of error by design, audit, and feedback of operational experience) Occupational/process safety Manual/control operations Routine operation Task analysis Job design Workplace design Interface design Physical environment evaluation Workload analysis Infrequent... 

Perform task analysis and classify skill, rule or knowledge-based behaviors involved in the scenario being evaluated. 

The third category of methods addressed in this chapter are error analysis and reduction methodologies. Error analysis techniques can either be applied in a proactive or retrospective mode. In the proactive mode they are used to predict possible errors when tasks are being analyzed during chemical process quantitative risk assessment and design evaluations. When applied retrospectively, they are used to identify the underlying causes of errors giving rise to accidents. Very often the distinction between task analysis and error analysis is blurred, since the process of error analysis always has to proceed from a comprehensive description of a task, usually derived from a task analysis. 

Human error tmalysis (HEA) is a systematic evaluation of the factors tliat influence tlie performance of human operators, maintenance staff, teclmicians, and otlier persomiel in tlie plant. HEA involves the evaluation of one of several types of task analysis, which is a metliod for describing tlie physical and enviromiiental characteristics of a task along witli tlie skills, knowledge, and capabilities required of tliose who perform the task. Tliis type of analysis can identify error-likely situations tliat can cause or lead to an accident. 

A new area of research concerns exposure assessment for beryllium in the production of nuclear weapons at nuclear defense industries. A safe level of exposure to beryllium is still unknown. Potential explanations include (1) the current exposure standard may not be protective enough to prevent sensitization, or (2) past exposure surveillance may have underestimated the actual exposure level because of a lack of understanding of the complexity of beryllium exposures. Task-based exposure assessment provides information not directly available through conventional sampling. It directly links exposure to specific activity associated with contaminant generation and provides in-depth evaluation of the worker s role in a specific task. In-depth task analysis is being used to examine physical, postural, and cognitive demands of various tasks. 

To cover these aspects when designing a software system, methods of work and more specific task analysis must be applied and ergonomic requirements have to be met. Furthermore, to validate if both task-related and interaction-related issues have been considered, an evaluation is necessary. 

The central result of eqn (6.11) can be played out both at the model level and using full quantum mechanical treatments of the electron spectrum. The most immediate route to a concrete result is to evaluate the electronic contribution to the free energy directly on the basis of the physics of the electron gas model. Recall that in this case, the electron density of states is of the form p E) oc J E. As a result, we are faced with the task of evaluating eqn (6.11) for the square-root density of states. As will be spelled out in the problems at the end of this chapter, the result of carrying out this analysis is... 

In the more complex sort of economic evaluation, cost-utility and cost-benefit analysis, the task of evaluating outcomes on a utility or even monetary scale must be addressed. A device which is used to do this is known as the standard gamble, ably discussed by Spiegelhalter, (1982) and also by Petitti (2000). We wish to evaluate the utility of a certain outcome, C, and to do so we consider that the patient may be offered instead a gamble G whose result will be with probability p the best possible outcome. 

Effective interactive system design thus comes from a basis in direct observation of users in their work environments rather than assumptions about the users or observations of their activities in contrived laboratory settings (Hackos and Redish 1998). Yet contextual tasks analysis is sometimes overlooked because developers assume they know users or that their user base is too diverse, expensive, or time consuming to get to know. In most cases, however, observation of a small set of diverse users can provide critical insights that lead to more effective and acceptable system designs. For usability evaluations, Nielsen (1993) found that the greatest payoff occurs with just three users. 

Implementation of sound design practices, including the use of requirements definition, user profile development, tasks analysis, and task allocation Setting usability objectives that focus around effectiveness, intuitiveness, and subjective perception Iterative usability evaluation Identification of users mental models Identification of appropriate metaphors... 

For those tasked with evaluating clinical risk alone, consequences unrelated to safety need to be consciously removed from the equation and not bias the analysis. As we will go on to discuss, objectivity is paramount in CRM and a tight definition of what constitutes clinical risk versus other types of risk is essential. 

In many studies, task demands are only assessed with subjective techniques. This approach is not adequate because there may often be, for various reasons, a considerable difference between the objective workload and the subjective evaluation by the employees. Hence, it is in most cases desirable to obtain objective data on task demands. The operationalization of demand as well as perfonnance measures deserves very careful consideration. It is often necessary to consult experts and to carry out an operational task analysis in order to obtain sufficient insight into the relevant specifications. 

The stationary state of the network of reactors is stable, if all roots A, of (13.8) have a negative real part. The necessary and sufficient conditions for this to hold are the Routh-Hurwitz conditions, see Theorem 1.2. The stationary state of the network, W, undergoes a stationary instability if = 0, see (1.36), and an oscillatory instability if = 0, together with > 0, A > 0, Z = 1,..., m — 2, see (1.38). The Routh-Hurwitz analysis can be used to determine, in principle, the stability properties of the steady state of any network, even inhomogeneous networks. This advantage is, however, balanced by the fact that it is a computationally expensive task to evaluate all the coefficients C of the characteristic polynomial and the Hurwitz determinants A . In our studies of instabilities in arrays of coupled reactors, we used symbolic computation software, namely Mathematica (Wolfram Research, Inc., Champaign, IL, 2002) and Maple (Waterloo Maple Inc., Waterloo, Ontario, 2002), to obtain exact, analytical expressions for the coefficients C of the characteristic polynomial (13.8) and the Hurwitz determinants A/ for arrays of up to six coupled reactors. 

According to this rating, a screening of the human performance is performed. Moreover, since a nominal task analysis has been performed to analyse all tasks in sequence, probabilities for human errors that can lead to deviations from the required sequence can be estimated. Critical PSFs have been also identified and their impact to the human error probability is evaluated with the FPE. Additionally, critical operating and recovery points needing improvements are identified. The imp act o f the se improvements to the overall hmnan performance is depicted through the use of the FPE tool. This whole process is explained with the use of a specific example. 

The effectiveness and validation of the representation method is not the only aspect to be considered for evaluating task analysis tools. Other critical aspects have to be considered ... 

Task criticalities evaluation connection between the phase of the task criticalities evaluation and the methods used for the task analysis itself (likely chance data collection phase is missing much of the information useful in the evaluation phase). 

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