The Process of Task Analysis

Industrial or occupational safety and health professionals have been involved for some time now in the analysis of tasks which must be performed in the workplace 

Task analysis differs from Job Safety Analysis in that the latter is a more simplified, global, higher function description of a job and its corresponding tasks assigned to one person and related to general safety. 

Task analysis outputs may serve a variety of system inputs. For example, task analysis may be used to obtain detailed information on a given work position, thereby providing data for selection, training, staffing level, procedure development and retrofit, communications, equipment review, feedback, supervisory control, and risk screening. 

TABLE 4.1 Human Behavior Considerations in System Design 

Peopie seldom consider the effects of surface friction on their abiiity to grasp and hoid an article 

Most people cannot estimate distances, clearances, or velocities very well (they tend to overestimate short and underestimate large distances) 

Most people do not watch where they place their hands and feet, especially in familiar surroundings 

People often utilize the first thing available as an aid in getting where they want to go or to manipulate or fix something 

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Blackmane, H. S., D. I. Gertman, and L. N. Haney (Sept. 1985). The Process of Task Analysis (SSDC-31), U.S. Department of Energy, System Safety Development Center, EG G Idaho, Inc., Idaho Falls. 

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. 

As discussed in Chapter 4, task analysis is a very general term that encompasses a wide variety of techniques. In this context, the objective of task analysis is to provide a systematic and comprehensive description of the task structure and to give insights into how errors can arise. The structure produced by task analysis is combined with the results of the PIF analysis as part of the error prediction process. 

It has been recognized that many of the time-consuming interactive tasks carried out by an expert during the process of spectral analysis could be done more efficiently by automated computational systems [6]. Over the past few years, this potential has been realized to some degree. Today automated methods for NMR structure determination are playing a more and more prominent role and can be expected to largely supersede the conventional manual approaches to solving three-dimensional protein structures in solution. 

The process of risk analysis consists of three individual circles risk assessment, risk management and risk communication. They are all linked to each other and even overlap in tasks. Proper functioning of this process is of key importance. 

On first sight, this problem seems impossible. The trick is not to focus on the immediate solution, but on the process of retrosynthetic analysis. Thus, the first task is to find a precursor to A that is an appropriately substituted cyclohexene. We can worry about how to make it (by a Diels-Alder reaction) later. 

The first questions to be considered when designing a control panel are what information is required and how much of it will be appropriate. Too little information may increase the amount of inference that the worker is required to make to predict the state of process parameters that are not directly displayed. This is especially important for emergency situations where the human information processing system is taxed heavily with many tasks. On the other hand, too much redimdant information can overload the worker. It is essential, therefore, that the information needs of the worker are identified through some form of task analysis and worker interviews. 

By visual inspection of an OAET it is possible to identify the elements of a process control task which are critical in responding to an initiating event. An important issue in the construction of OAETs is the level of task breakdown. If the overall task is redescribed to very small subtasks it might be difficult to gain insights from the OAET because it Ccin become relatively unwieldy. Hierarchical Task Analysis provides a useful framework for the... 

Although checklists are a useful way of transferring information about human-machine interaction to designers and engineers, they are not a standalone tool and they cannot provide a substitute for a systematic design process. The main concern with checklists is that they do not offer any guidance about the relative importance of various items that do not comply with the recommendations, and the likely consequences of a failure due to a noncompliance. To overcome such problems, checklists should be used in combination with other methods of task analysis or error analysis that can identify the complexities of a task, the relationships among various job components, and the required skills to perform the task. 

During this stage of the qualitative analysis, a PIF analysis is performed that considers those factors which will determine the probability of error for the type of task under consideration. A structured form of PIF analysis such as the HFA tool described in Section 2.7.2 will facilitate this process. 

These refer to the control of a chemical process and include planning for familiar tasks (e.g., change type of fuel-firing in a furnace) or planning for familiar but infrequent tasks (e.g., start-up or shutdown a furnace). Methods of task analysis and error analysis can be used to analyze well-established strategies that operators use to perform procedural tasks and identify the user s information needs. An implication for display design would be that all information needed... 

Task Analysis and Error Analysis of the Blowdown Operation Task analysis was carried out in order to organize all the performance data about the way that workers process information, the nature of the emergency and the way that decisions are made. Figure 7.20 shows a tabular task analysis of the workers response to a significant unignited gas leak in MSM. The analysis was a combination of a tabular HTA and a CADET analysis (see Chapter 4). Human error analysis identified the major human failure modes which could affect time to blowdown (see Table 7.2). 

The collection of examples is extensive and includes relatively simple data analysis tasks such as polynomial fits they are used to develop the principles of data analysis. Some chemical processes will be discussed extensively they include kinetics, equilibrium investigations and chromatography. Kinetics and equilibrium investigations are often reasonably complex processes, delivering complicated data sets and thus require fairly complex modelling and fitting algorithms. These processes serve as examples for the advanced analysis methods. 

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