ICS3211_lecture 9_2022.pdf
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The document discusses various methods for testing and evaluating user interfaces, including expert review, heuristic evaluation, cognitive walkthrough, usability testing, surveys, acceptance tests, and automated evaluation. It provides details on each method, such as when they are used, how they are conducted, their benefits and limitations. The goal of evaluation and testing is to improve interfaces and ensure they meet user needs.
ICS3211_lecture 9_2022.pdf
- 1. ICS3211 - Intelligent Interfaces II Combining design with technology for effective human- computer interaction Week 9 Department of AI, University of Malta, 2022 1
- 2. Testing & Evaluation Week 9 overview: • The What, Why and When of Evaluation & Testing • Testing: expert review and lab testing • Evaluation: formative/summative • Evaluation: heuristic, cognitive walkthrough, usability testing • Case study: evaluating different interfaces 2
- 3. Learning Outcomes At the end of this session you should be able to: • describe different forms of evaluation for different interfaces; • compare and contrast the different evaluation methods with the different contexts and identify the best one to use; • list various rules for the heuristic evaluation (Schniederman & Nielsen); • list the various types of usability testing involved in evaluation; • combine the various evaluation methods to come up with a method that is most suitable to the project chosen. 3
- 4. Introduction • Why evaluate? • Designers become too entranced • What I like • Sunk cost fallacy • Experienced designers know extensive testing is required • How do you test? • A web site? • Air traf fi c control system? • When do you test? 4
- 5. What to Evaluate? • What to evaluate may range from screen functions, aesthetic designs to work fl ows; • Users of an ambient display may want to know if it changes people’s behaviour; • Class Activity: What aspects would you want to evaluate in a VR system designed to change users’ behaviour (you can choose which behaviour you would want to see modi fi ed). Log in to Moodle VLE. 5
- 6. • Evaluation stages depends on product being designed; • Formative evaluations - evaluation done to check a product continues to meet users’ needs • Summative evaluations - evaluation done to assess the success of a product 6 Ways of Categorising Evaluation
- 7. Evaluation Categories • Cognitive Psychological Approaches • Social Psychology Methods - Interviews and Questionnaires • Social Science Methods • Engineering Approaches 7
- 8. Expert Review • Colleagues or Customers • Ask for opinions • Considerations: • What is an expert? User or designer? • Half day to week 8
- 9. Formal Usability Inspection • Experts hold courtroom-style meeting • Each side gives arguments (in an adversarial format) • There is a judge or moderator • Extensive and expensive • Good for novice designers and managers 9
- 10. Expert Reviews • Can be conducted at any time in the design process • Focus on being comprehensive rather than being speci fi c on improvements • Example review recommendations • Change log in procedure (from 3 to 5 minutes, because users were busy) • Reordering sequence of displays, removing nonessential actions, providing feedback. • Also come up with features for future releases 10
- 11. Expert Review • Placed in situation similar to user • Take training courses • Read documentation • Take tutorials • Try the interface in a realistic work environment (complete with noise and distractions) • Bird’s eye view • Studying a full set of printed screens laid on the fl oor or pinned to the walls • See topics such as consistency 11
- 12. Heuristic Evaluation • Give Expert heuristic, ask them to evaluate • Shneiderman's "Eight Golden Rules of Interface Design" • Nielsen’s Heuristics 12
- 13. Shneiderman's "Eight Golden Rules of Interface Design • Strive for consistency • Enable frequent users to use shortcuts • Offer informative feedback • Design dialog to yield closure • Offer simple error handling • Permit easy reversal of actions • Support internal locus of control • Reduce short-term memory load 13
- 14. Nielsen’s Heuristics • Visibility of system status • Match between system and the real world • User control and freedom • Consistency and standards • Error prevention • Recognition rather than recall • Flexibility and ef fi ciency of use • Aesthetic and minimalist design • Help users recognize, diagnose, and recover from errors • Help and documentation 14
- 15. Consistency Inspection • Verify consistency across family of interfaces • Check terminology, fonts, color, layout, i/o formats • Look at documentation and online help • Also can be used in conjunction with software tools 15
- 16. Cognitive Walkthrough • Experts “simulate” being users going through the interface • Tasks are ordered by frequency • Good for interfaces that can be learned by “exploratory browsing” • Usually walkthrough by themselves, then report their experiences (written, video) to designers meeting • Useful if application is geared for group the designers might not be familiar with: • Military, Assistive Technologies 16
- 17. Metaphors of human Thinking (MOT) • Experts consider metaphors for fi ve aspects of human thinking • Habit • Stream of thought • Awareness and Associations • Relation between utterances and thought • Knowing • Appears better than cognitive walkthrough and heuristic evaluation 17
- 18. Types of Evaluation • Controlled settings involving users • usability testing • living labs • Natural settings involving users • fi eld studies • Any settings not involving users 18
- 19. Usability Testing and Labs • 1980s, testing was luxury (but deadlines crept up) • Usability testing was incentive for deadlines • Fewer project overlays • Sped up projects • Cost savings • Labs are different than academia • Less general theory • More practical studies 19
- 20. Staff • Expertise in testing (psych, hci, comp sci) • 10 to 15 projects per year • Meet with UI architect to plan testing (Figure 4.2) • Participate in early task analysis and design reviews • T – 2-6 weeks, creates study design and test plan • E.g. Who are participants? Beta testers, current customers, in company staff, advertising • T -1 week, pilot test (1-3 participants) 20
- 21. Participants • Labs categorize users based on: • Computing background • Experience with task • Motivation • Education • Ability with the language used in the interface • Controls for • Physical concerns (e.g. eyesight, handedness, age) • Experimental conditions (e.g. time of day, physical surroundings, noise, temperature, distractions) 21
- 22. Recording Participants • Logging is important, yet tedious • Software to help • Powerful to see people use your interface • New approaches: eye tracking • IRB items • Focus users on interface • Tell them the task, duration 22
- 23. Thinking Aloud • Concurrent think aloud • Invite users to think aloud • Nothing they say is wrong • Don’t interrupt, let the user talk • Spontaneous, encourages positive suggestions • Can be done in teams of participants • Retrospective think aloud • Asks people afterwards what they were thinking • Issues with accuracy • Does not interrupt users (timings are more accurate) 23
- 24. Types of Usability Testing • Paper mockups and prototyping • Inexpensive, rapid, very productive • Low fi delity is sometimes better 24 http://expressionflow.com/wp-content/uploads/2007/05/paper-mock-up.png http://user.meduni-graz.at/andreas.holzinger/holzinger/papers%20en/
- 25. Types of Usability Testing • Discount usability testing • Test early and often (with 3 to 6 testers) • Pros: Most serious problems can be found with 6 testers. Good for formative evaluation (early) • Cons: Complex systems can’t be tested this way. Not good for summative evaluation (late) • Competitive usability testing • Compare against prior or competitor’s versions • Experimenter bias, be careful to not “prime the user” • Within-subjects is preferred 25
- 26. Types of Usability Testing • Universal usability testing • Test with highly diverse • Users (experience levels, ability, etc.) • Platforms (mac, pc, linux) • Hardware (old (how old is old?) -> latest) • Networks (dial-up -> broadband) • Field tests and portable labs • Tests UI in realistic environments • Beta tests 26
- 27. Types of Usability Testing • Remote usability testing (via web) • Recruited via online communities, email • Large n • Dif fi culty in logging, validating data • Software can help • Can You Break this Test • Challenge testers to break a system • Games, security, public displays 27
- 28. Limitations • Focuses on fi rst-time users • Limited coverage of interface features • Emergency (military, medical, mission-critical) • Rarely used features • Dif fi cult to simulate realistic conditions • Testing mobile devices • Signal strength • Batteries • User focus • Yet formal studies on user studies have identi fi ed • Cost savings • Return on investment (Sherman 2006, Bias and Mayhew 2005) 28
- 29. Survey Instruments • Questionnaires • Paper or online (e.g. surveymonkey.com) • Easy to grasp for many people • The power of many can be shown • 80% of the 500 users who tried the system liked Option A • 3 out of the 4 experts like Option B • Success depends on • Clear goals in advance • Focused items 29
- 30. Designing survey questions • Ideally • Based on existing questions • Reviewed by colleagues • Pilot tested • Direct activities are better than gathering statistics • Fosters unexpected discoveries • Important to pre-test questions • Understandability • Bias 30
- 31. Likert Scales • Most common methodology • Strongly Agree, Agree, Neutral, Disagree, Strongly Disagree • 5, 7, 9-point scales • Examples • Improves my performance in book searching and buying • Enables me to search and buy books faster • Makes it easier to search for and purchase books 31
- 32. Most Used Likert-scales • Questionnaire for User Interaction Satisfaction • E.g. questions • How long have you worked on this system? • System Usability Scale (SUS) – Brooke 1996 • Post-Study System Usability Questionniare • Computer System Usability Questionniare • Software usability Measurement Inventory • Website Analysis and MeasureMent Inventory • Mobile Phone Usability Questionnaire • Validity, Reliability 32
- 33. Bipolar Semantically Anchored • Coleman and Williges (1985) • Pleasant versus Irritating • Hostile 1 2 3 4 5 6 7 Friendly • If needed, take existing questionnaires and alter them slightly for your application 33
- 34. Acceptance Tests • Set goals for performance • Objective • Measurable • Examples • Mean time between failures (e.g. MOSI) • Test cases • Response time requirements • Readability (including documentation and help) • Satisfaction • Comprehensibility 34
- 35. Let’s discuss You want your project to be user friendly. • Choose Schneiderman or Nielsen’s heuristics to provide an evaluation methodology: • What kind of setting would you use? • How much control would you want to exert? • Which methods are recorded and when will they be recorded? 35
- 36. Acceptance Tests • By completing the acceptance tests • Can be part of contractual ful fi llment • Demonstrate objectivity • Different than usability tests • More adversarial • Neutral party should conduct that • Ex. Video game and smartphone companies • App Store, Microsoft, Nintendo, Sony 36
- 37. Evaluation during use • Evaluation methods after a product has been released • Interviews with individual users • Get very detailed on speci fi c concerns • Costly and time-consuming • Focus group discussions • Patterns of usage • Certain people can dominate or sway opinion • Targeted focus groups 37
- 38. Continuous Logging • The system itself logs user usage • Video game example • Other examples • Track frequency of errors (gives an ordered list of what to address via tutorials, training, text changes, etc.) • Speed of performance • Track which features are used and which are not • Web Analytics • Privacy? What gets logged? Opt-in/out? • What about companies? 38
- 39. Online and Telephone Help • Users enjoy having people ready to help (real-time chat online or via telephone) • E.g. Net fl ix has 8.4 million customers, how many telephone customer service reps? • 375 • Expensive, but higher customer satisfaction • Cheaper versions use Bug Report systems 39
- 40. Automated Evaluation • Software for evaluation • Low level: Spelling, term concordance • Metrics: number of displays, tabs, widgets, links • World Wide Web Consortium Markup Validation • US NIST Web Metrics Testbed • New research areas: Evaluation of mobile platforms 40
- 41. Case Study • Computer Game: • Physiological responses used to evaluate users’ experiences; • Video of participants playing - observation; • User satisfaction questionnaire; • Possibilities of applying crowdsourcing for online performance evaluations 41