Which three measures are needed to establish how usable a product is?
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Product Responsiveness, Stability and Consistency
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User Effectiveness, Efficiency and Satisfaction
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Style guide conformance, Fault tolerance, Size of manual
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User Happiness, Competence, Motivation
The ISO 9241-11 standard defines usability through three core metrics: Effectiveness (accuracy and completeness of goals), Efficiency (resources expended in relation to effectiveness), and Satisfaction (freedom from discomfort and positive attitudes). These are the definitive measures for assessing product usability.
ISO 9241-11 defines usability in terms of three core measures: Effectiveness (can users accomplish their goals accurately/completely), Efficiency (resources expended, like time, to achieve those goals), and Satisfaction (users' subjective comfort/acceptability). This is the standard, widely-cited usability framework. The other options list plausible-sounding but non-standard groupings (stability/consistency, style-guide conformance, happiness/competence/motivation) that aren't the recognized three usability measures.