Usability
The International Organization for Standardization gives usability a three-criterion definition: a widget is more usable when it is more effective, efficient, and satisfying to use, assuming it’s being used for the right purpose and by the right target audience (ISO DIS 9241–11, 1998). Effectiveness and efficiency are fairly straightforward indicators of whether the widget does what it’s supposed to do. Satisfaction is a question of whether the user is comfortable using the widget and does not suffer any undue stress or frustration while using it.
There are many ways to measure usability, and measurements vary widely in their ease of execution, content targeted, reliability, and validity. Dumas and Salzman (2006) give a comprehensive review of these methods. Roughly ordered from clean and expedient to muddy and comprehensive, they are summarized below:
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Heuristic evaluations
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System Usability Scale (SUS)
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Cognitive walkthroughs
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Surveys
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Interviews
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Focus groups
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Ethnography
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Dumas, J. S., & Salzman, M. C. (2006). Usability assessment methods. Reviews of human factors and ergonomics, 2(1), 109-140.
International Organization for Standardization. (2018). Ergonomic requirements for office work with visual display terminals (Standard no. 9241-11). Retrieved from https://www.iso.org/obp/ui/#iso:std:iso:9241:-11:ed-2:v1:en.
