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Evaluation methods


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Introduction to usability

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Evaluation methods

  1. 1. Media Design course Autumn 2016 Evaluation Methods Usability
  2. 2. INDEX 1. Introduction 2. Usability metrics 3. Usability inspection methods 4. User-based evaluation 5. Usability evaluation methods 6. Planning evaluation
  3. 3. 1. INTRODUCTION The effectiveness, efficiency and satisfaction with which specified users achieve specified goals in particular environments. Definition of usability ISO/IEC 9126
  4. 4. 1. INTRODUCTION Usability quality components (Nielsen, 2012) •  Learnability •  Efficiency •  Memorability •  Errors •  Satisfaction
  5. 5. User behavior has low tolerance for difficult designs or slow sites. If they don’t understand the functioning of the sites, they will leave. Why investing in usability? 1. INTRODUCTION •  Offer a good return on investment •  Can bring competitive advantage •  Help making the design adequate. Usability studies:
  6. 6. EFFECTIVENESS The accuracy and completeness with which users achieve specified goals Usability metrics (ISO/IEC 9126-4 – Metrics) •  Completion rate •  Number of errors Errors can be unintended actions, slips, mistakes or omissions that a user makes while attempting a task. Errors detected during user testing should be described, rated and classified. 2. USABILITY METRICS
  7. 7. Usability metrics (ISO/IEC 9126-4 – Metrics) •  Overall relative efficiency The overall relative efficiency uses the ratio of the time taken by the users who successfully completed the task in relation to the total time taken by all users. 2. USABILITY METRICS EFFICIENCY The resources expended in relation to the accuracy and completeness with which users achieve goals. •  Time-based efficiency This value helps identify the average time spent on a task (which might be successfully completed or not)
  8. 8. Usability metrics (ISO/IEC 9126-4 – Metrics) 2. USABILITY METRICS SATISFACTION The comfort and acceptability of use. •  Task level satisfaction Just after users attempt a task they should be given a questionnaire to measure how difficult that task was. A popular post-task questionnaire is the SEQ (Single Ease Question) consisting in 1 question.
  9. 9. 2. USABILITY METRICS •  Test level satisfaction At the end of the test, each participant fills a questionnaire to assess their general level of satisfaction