To understand usability it is important to not only measure user performance (effectiveness and efficiency) but also satisfaction. Established questionnaires will give more reliable and repeatable results than ad hoc questionnaires.
Overall satisfaction: SUS
SUS (System Usability Scale) is a 10-item questionnaire that gives an overview of satisfaction with software. It was developed by John Brooke, and is freely available for use providing acknowledgement is made of the source.
Satisfaction profile: SUMI
SUMI (Software Usability Measurement Inventory) is a 50 item questionnaire that measures five aspects of user satisfaction (Likability, Efficiency, Helpfulness, Control and Learnability), and scores them against expected industry norms. It can be purchased from HFRG. The INUSE Handbook explains how to use SUMI.
User interface satisfaction: QUIS
QUIS (Questionnaire for User Interaction Satisfaction) is similar to SUMI, but measures attitude towards eleven interface factors (screen factors, terminology and system feedback, learning factors, system capabilities, technical manuals, on-line tutorials, multimedia, voice recognition, virtual environments, internet access, and software installation). It does not have industry norms. QUIS can be purchased from the University of Maryland.
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