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5 Case Studies
Pages 91-126

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From page 91...
... This example provides a "notional" application of human factors methods and potential implementation of the incremental commitment model. The case study illustrates the theme of designing to accommodate changing conditions and requirements in the workplace.
From page 92...
... This case study illustrates the successful implementation of well-known HSI methods, including contextual inquiry, prototyping and simulations, cognitive walkthroughs for estimating use-error-induced operational risks, iterative design, and usability evaluations that include testing and expert reviews. The importance of the incremental commitment model in phased decision making and the value of shared representations is also highlighted.
From page 93...
... borders. The growing need for UAS personnel, combined with the current shortage, points to another theme of this report: the need for human-system integration to accommodate changing conditions and requirements in the workplace.
From page 94...
... Up-front analyses, such as interviews of UAS operators, observations of operations of 2:1 systems, examination of mishap reports, understanding of the literature and data, an analysis of the 2:1 workload, event data analysis targeted at communications in the 2:1 UAS system, application of models of operator workload, and work flow analysis are all methods that could be used to explore the HSI issues in the current UAS system. There is much that could come from this kind of up-front analysis.
From page 95...
... The HSI methods in the later stages include interviews and observations in conjunction with the newly designed system and usability testing. Some of the same methods used in up-front analysis (e.g., event data analysis, participatory analysis)
From page 96...
... It can be integrated throughout the design life cycle with other engineering methods. It is also clear that the HSI activities serve to reduce human factors risks along the way and make evident the human factors issues that are at stake, so that these issues can be considered as they trade off with other design issues.
From page 97...
... Our example focuses on radiation screening at seaports, which have a particularly complex operational nature. Seaports are structured to facilitate the rapid offloading of cargo containers from ocean-going vessels, provide temporary storage of the containers, and provide facilities for trucks and trains to load containers for transport to their final destination.
From page 98...
... Design and deployment of radiation portal monitoring (RPM) systems for seaport operations engages the incremental commitment model for ensuring commitments from the stakeholders and to meet the fundamental technical requirement of screening 100 percent of arriving international cargo containers for illicit radioactive material.
From page 99...
... The work domain analysis has typically focused on gaining a rapid understanding of relatively complicated seaport operations in order to evaluate technology insertion opportunities and to better understand design requirements. In contrast to work domain analysis oriented toward cognitive decision aids, which requires time-intensive collaboration with subject matter experts, the RPM analysis worked at a coarser level to characterize staff functions and interactions, material flow, and operational tempo.
From page 100...
... Shared Representations Used to Communicate The rapid-paced nature of the RPM program places a premium on effective communication between human-system integration and the engineering disciplines. In this program, fairly simple communication mechanisms that use graphics or presentation methods adapted from engineering have the best chance of successful communication.
From page 101...
... Accommodation to Changing Conditions and Workplace Requirements The RPM program started with a set of baseline designs for seaports that involved a cargo container passing through an exit gate. As the program expanded to a wider range of port operations, numerous variations in the container-processing operations became apparent.
From page 102...
... The critical issue for seaports is that current operations do not predict future operations; the rapid expansion of imports will fundamentally alter how high-volume ports process their cargo, and HSI studies will be an important element of adapting the security screening technologies to evolving operational models. Scalable Methods The RPM program is large in scale -- involving geographically distributed installations on a nationwide basis, multiple personnel, government agencies and private-sector stakeholders -- and seaports are an element of
From page 103...
... Incremental Growth of System Definition and Stakeholder Commitment The objective of minimal disruption to ongoing seaport operations and the need to identify traffic choke points and screening opportunities require considerable up-front analysis, as well as continuing evaluation of impact as individualized deployments are designed. The general activities in this category include • initial site surveys to identify choke points.
From page 104...
... For example, HSI operational studies of straddle carrier cargo operations were undertaken midway through seaport deployments, when it was recognized that existing technology solutions could not be adapted to that type of operation. The risk of using existing technology was that seaport operations would need to fundamentally change -- this would lead to an unacceptable
From page 105...
... The infuser includes a large touchscreen color display and can be powered by either A/C power or rechargeable batteries. To ensure that the infuser has an easy-to-use user interface, the development of the product was based on a user-centered design approach.
From page 106...
... In the final phases of development, extensive usability testing in simulated patient environments was conducted to ensure design intent has been implemented and that ease of use and usability objectives were met. Throughout the development process, iterative risk analysis, evaluation, and control were conducted in compliance with the federally regulated design control process (see Figures 5-5 and 5-6)
From page 107...
... 107 CASE STUDIES FIGURE 5-5 Two channel IV pumps with left channel illuminated. Photograph courtesy of Hospira, Inc.
From page 108...
... Many of the interim project deliverables, such as fully interactive simulations of graphical user interfaces (GUI) , were in the form of shared representations of the design, so that all development team members had the same understanding of the product requirements during the development cycle.
From page 109...
... Again, business risks were assessed. This step is typical in an ICM development approach.
From page 110...
... Field studies and contextual inquiry were planned as follow-on research to verify the need for these features and to collect more detail on how they would be designed. Types of programmable therapies.
From page 111...
... This is an example of incremental growth and stakeholder commitment in the design process. Large color touch screen.
From page 112...
... These auditory alarms were later subjected to extensive lab and field studies for effectiveness and acceptability. An early beta test in actual hospital settings with extended use subsequently showed user dissatisfaction with the harshness of some of the alarm melodies.
From page 113...
... Risk analyses for business and safety risks were updated to include these design decisions. Industrial design models were built to prototype these concepts, and these working prototypes were subjected to subsequent lab-based usability testing.
From page 114...
... In all cases, these decisions were verified and validated with subsequent data from usability tests and from field trials. Design Process Details The development of the Symbiq™ IV Pump followed the acknowledged best practices iterative user-centered design process as described in medical device standards (ANSI/AAMI HE 74:2001, IEC 60601-1-6:2004, and FDA human factors guidance for medical device design controls)
From page 115...
... Early use-error risk analysis highlighted tasks that were likely to have high risk, with particular attention to setting usability objectives to ensure that these user interface design mitigations were effective. Experience with earlier IV pump designs and user performance in usability tests also influenced the setting of these usability objectives.
From page 116...
... Prototyping and iterative Design was iterated many times over through a series of at least design 12 usability test cycles. Usability testing A series of formative usability tests were conducted in both usability-testing labs and in the patient simulator.
From page 117...
... Investigate the use of alternative statistical analysis methods such as Bayesian statistics to conduct summative usability tests. Field studies have the advantage of giving Research techniques that are more efficient in real-world validation to lab-based providing the kind of postmarket surveillance usability evaluations, but are time and data that can be obtained from field studies.
From page 118...
... Select rate Select volume Select rate Enter digits Enter digits Enter digits and press and press and press select select select Select volume Select time Select time Enter digits Enter digits Enter digits and press and press and press select select select Press next Press Start Verify program Program "A" FIGURE 5-7 Illustrative task flow diagram from the task analysis.
From page 119...
... • Flash animations are excellent examples of shared representations because they were directly used in the product requirements document to specify to software engineering exactly how the GUI was to be developed. All team discussions regarding GUI design were focused exclusively on the Flash animation shared representations of the Symbiq™ user interface.
From page 120...
... based graphical user interface, critical pump-handling tasks were included as well, such as IV pump mounting and dismounting on typical IV poles. Tests of Alarm Criticality and Alerting The initial alarm formative usability studies, described earlier, had the goal of selecting alarms that would be alerting, attention getting, and properly convey alarm priority, as well as communicating appropriate actions.
From page 121...
... Trailing zeros have been eliminated for whole numbers, e.g., 50.0 will be 50. When a value entered is not within specified 1 8 Study report for rule sets, a warning appears and the override User Study soft limits icon appears.
From page 122...
... In one of the intermediate formative usability tests, a patient simulator facility was used at a major teaching hospital. Users performed a variety of critical tasks in a simulated room in an intensive care unit, in which other medical devices interacted and produced noises and other distractions.
From page 123...
... Numerous suggestions for improvement in the TIPS cards themselves as well as the user interface came from this work, including how to reset the air-in-line alarm and how to address the alarm and check all on-screen help text for accuracy. Validation Usability Tests Two rounds of summative usability testing were conducted, again with experienced nurses performing critical tasks identified during the task analysis, including those with higher risk values in the risk analysis.
From page 124...
... Revised Risk Analysis As part of the incremental commitment model, the risk analysis was iterated and revised as the product development matured. FMEAs were updated for three product areas, which were safety-critical risks associated with the user interface, the mechanical and electrical subsystems, and the product manufacturing process.
From page 125...
... 6. Design to accommodate changing conditions and requirements in the workplace (the use of iterative design and the incremental commitment model)


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