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- Liu, Yuanhua, 1971, et al.
(författare)
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Considering the importance of user profiles in interface design
- 2009
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Ingår i: User Interfaces. ; , s. 23-
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- User profile is a popular term widely employed during product design processes by industrial companies. Such a profile is normally intended to represent real users of a product. The ultimate purpose of a user profile is actually to help designers to recognize or learn about the real user by presenting them with a description of a real user’s attributes, for instance; the user’s gender, age, educational level, attitude, technical needs and skill level. The aim of this chapter is to provide information on the current knowledge and research about user profile issues, as well as to emphasize the importance of considering these issues in interface design. In this chapter, we mainly focus on how users’ difference in expertise affects their performance or activity in various interaction contexts. Considering the complex interaction situations in practice, novice and expert users’ interactions with medical user interfaces of different technical complexity will be analyzed as examples: one focuses on novice and expert users’ difference when interacting with simple medical interfaces, and the other focuses on differences when interacting with complex medical interfaces. Four issues will be analyzed and discussed: (1) how novice and expert users differ in terms of performance during the interaction; (2) how novice and expert users differ in the perspective of cognitive mental models during the interaction; (3) how novice and expert users should be defined in practice; and (4) what are the main differences between novice and expert users’ implications for interface design. Besides describing the effect of users’ expertise difference during the interface design process, we will also pinpoint some potential problems for the research on interface design, as well as some future challenges that academic researchers and industrial engineers should face in practice.
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- Liu, Yuanhua, 1971, et al.
(författare)
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Learning From Experienced User in Real Life.
- 2007
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Ingår i: 39th Annual Congress of the Nordic Ergonomics Society (NES), Oct 1-3 2007, Lysekil, Sweden.
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Konferensbidrag (refereegranskat)abstract
- User-centered design (UCD) has become a popular design philosophy and process in recent years. According to this design philosophy, end users’ needs, expectations and limitations when interacting with interfaces or systems are also taken into consideration at each stage of the design process. At the practical usability evaluation stage, how to select test subjects as end users always concerns the reliability of the evaluation results. In a small pilot study, three usability evaluation methods were employed to evaluate the experienced users’ performance on a simple interface, the interface of a Whirlpool microwave oven in a lunchroom at a working-place. The purpose of the study was to investigate how well experienced users handled the interface by performing casual tasks. The aim was to obtain proposals from the evaluation results for future redesign issues. Three usability evaluation methods were used in the study; i.e. Heuristic evaluation (HE), Thinking-Aloud method (TA), and Co-discovery method (CO). Seven typical task scenarios which reflect the typical main functions in practical daily usage of a microwave oven were selected for the evaluation. Altogether sixteen staff members of the working-place participated in the empirical tests. The results from the three methods were compared to each other, in terms of prediction on problem severity, task completion time, and satisfaction. Subjective assessment on task scenarios was also made in the end of each evaluation session. Statistical T-test and Mann-Whitney test were used in the analysis of the results. The results showed that all the test subjects failed in completing several task scenarios, which promotes designers and human factors engineers to reconsider the practical usage and efficiency of multi-functionality on product design and users’ expectations on interface design. In addition, the results also implied some interesting findings and differences among the three evaluation methods, which provide useful information for selecting usability evaluation methods.
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- Liu, Yuanhua, 1971, et al.
(författare)
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Usability Evaluation of a GUI Prototype for a Ventilator Machine.
- 2005
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Ingår i: International Journal of Clinical Monitoring and Computing. - : Springer Science and Business Media LLC. - 0167-9945 .- 1387-1307 .- 1573-2614. ; 18:5-6, s. 365-372
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Information presentation on the monitor screen of ventilator machines affects nurses' response and decision-making during ventilation treatment. The purpose of this study is to evaluate whether a new GUI (graphical user interface) prototype, the so-called circular displayprototype can make deviations easy to detect. Method. A numerical display prototype was made and used as a reference displ ay in the evaluation. Six task scenarios that involved parameter changes were selected to simulate a real situation under volume control (VC) mode during ventilation treatment. Usability tests with the two display designs were carried out in a usability laboratory. Twenty medical nursing students participated as test subjects in the usability tests. Results. The objective results showed that the graphical circular display had an advantage over the numerical display in interpreting parameter changes, but not in reducing the error rates for detecting the number of parameter changes or for forming an overall picture of the patient's situation. Furthermore, the circular display prototype did not improve the detection time. Conclusions. Although the majority of the test subjects preferred the graphical circular display, the results implied that several aspects of this prototype should be improved in a future development study.
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- Liu, Yuanhua, 1971
(författare)
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Usability Evaluation of Medical Technology: Investigating the Effect of User Background and Users' Expertise
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Medical devices play a major role in diagnosis and therapeutics in the healthcare systems. The basic features of medical devices concern safety and efficient clinical performance. Nowadays, usability evaluation is an important part of the design process of medical devices. The aims of this thesis work were to investigate the effect of user profiles on usability evaluation results and to provide practical advice on choice of users as test subjects when conducting usability evaluations of medical devices. Five studies, with analytical and empirical evaluation approaches with different foci, were included in the work. In the studies, consideration was given to user background and users’ expertise as well as to user interfaces of different levels of complexity. The user background aspect was taken as the focus for the analytical evaluation approach, while users’ expertise was taken as the focus for the empirical evaluation approach. Cognitive Walkthrough was employed as an example of an analytical evaluation method to investigate user background, while usability tests were used as an example of empirical evaluation method to investigate users’ expertise. The results showed that medical device user background settings can influence the outcome of an analytical evaluation results, i.e. when more ergonomic factors were included in the user background settings, a wider range of usability problems were detected. User expertise is an important factor for the results of empirical usability tests. Users’ familiarity with tasks can be used as an important criterion for classification of user expertise. The quantitative analysis of the empirical evaluations implies that the effect of users’ expertise may be invisible when interacting with a simple user interface, but visible when interacting with a more complex user interface. Expert users outperformed novice users when interacting with a complex interface but not when interacting with a simple interface.The qualitative analysis of verbal explanations and statements, causes of errors and redesign proposals stressed the differences between novice and expert users in terms of decision-making, presentation and judgment, which implied that expert users’ use experience and novice users’ interaction experience differ in contributing to product design and development. Insufficient domain and interaction knowledge were consistently identified as typical causes of errors for novice users. The differences of information organization between previously experienced user interfaces and the interfaces interacted in the usability tests affected expert users’ task completion. Expert users made task-related errors due to terminology issues and interaction-related errors due to their ‘old’ mental model of how to interact with the user interface. Based on the results, different strategies are suggested to be used when choosing test subjects for usability evaluations in different interaction situations. A guideline and some practical advices were proposed as well to medical industrial companies about how to conduct usability evaluations on medical devices.
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