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How to measure usability is an important question in HCI research and user interface evaluation. We review current practice in measuring usability by categorizing and discussing usability measures from 180 studies published in core HCI journals and proceedings. The discussion distinguish several problems with the measures, including whether they actually(More)
Usability comprises the aspects effectiveness, efficiency, and satisfaction. The correlations between these aspects are not well understood for complex tasks. We present data from an experiment where 87 subjects solved 20 information retrieval tasks concerning programming problems. The correlation between efficiency, as indicated by task completion time,(More)
Reading of electronic documents is becoming increasingly important as more information is disseminated electronically. We present an experiment that compares the usability of a linear, a fisheye, and an overview+detail interface for electronic documents. Using these interfaces, 20 subjects wrote essays and answered questions about scientific documents.(More)
Usability problems predicted by evaluation techniques are useful input to systems development; it is uncertain whether redesign proposals aimed at alleviating those problems are likewise useful. We present a study of how developers of a large web application assess usability problems and redesign proposals as input to their systems development. Problems and(More)
Think-aloud testing is a widely employed usability evaluation method, yet its use in practice is rarely studied. We report an explorative study of 14 think-aloud sessions, the audio recordings of which were examined in detail. The study shows that immediate analysis of observations made in the think-aloud sessions is done only sporadically, if at all. When(More)
We present an exploration of reading patterns and usability in visualizations of electronic documents. Twenty subjects wrote essays and answered questions about scientific documents using an overview+detail, a fisheye, and a linear interface. We study reading patterns by progression maps that visualize the progression of subjects' reading activity, and by(More)
We discuss the impact of cultural differences on usability evaluations that are based on the thinking-aloud method (TA). The term 'cultural differences' helps distinguish differences in the perception and thinking of Westerners (people from Western Europe and US citizens with European origins) and Easterners (people from China and the countries heavily(More)
Rotation of three-dimensional objects by a two-dimensional mouse is a typical task in computer-aided design, operation simulations, and desktop virtual reality. The most commonly used rotation technique is a virtual trackball surrounding the object and operated by the mouse pointer. This article reviews and provides a mathematical foundation for virtual(More)