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ICS 463, Intro to Human Computer Interaction Design: 11. Predictive Evaluation

ICS 463, Intro to Human Computer Interaction Design: 11. Predictive Evaluation. Dan Suthers. Why Predictive Testing. User testing is expensive and time consuming, and requires a prototype (although I strongly encourage you to always do at least some of it)

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ICS 463, Intro to Human Computer Interaction Design: 11. Predictive Evaluation

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  1. ICS 463, Intro to Human Computer Interaction Design: 11. Predictive Evaluation Dan Suthers

  2. Why Predictive Testing • User testingis expensive and time consuming, and requires a prototype(although I strongly encourage you to always do at least some of it) • Predictive techniquesuse expertise of human-computer interaction specialists (in person or via heuristics or models they develop) to identify usability problems without testing or (in some cases) prototypes

  3. Usage Simulation (Expert Review) • Pretend you are a novice user; identify usabilty problems • Requires • Expertise in HCI • Expertise in the application area • Ability to role play the novice • Objectivity (not a developer) • Problems • Bias of experts: use more than one • Hard to find experts • Novices do the darndest things!

  4. Walkthroughs • Structured form of usage simulation • Identify task, context, and user population • Walk through task, predicting user behavior • Variations: • Cognitive walkthrough: simulate cognitive processing of user … looks tedious! • Pluralistic walkthrough: multiple types of experts

  5. Heuristic Evaluation (Nielsen) • Inspection guided by usabilityheuristics • Speak the users’ language • Minimize user memory load • Be consistent • Provide feedback • Provide clearly marked exits … • Two passes • Inspect flow of interface from screen • Inspect each screen one at a time against heuristics • 75% of the problems with 5 evaluators Give it a try!

  6. Keystroke Level Modeling • Simulates expert behavior • No users or prototype needed! • Input: • Specification of functionality • Task analysis • Add time for physical & mental acts • Keystroking, pointing, homing, drawing • Mental operator • System response

  7. Keystroke Modeling Example Save a file in application using mouse and pull down menu 1. Initial homing to mouse T_H = 0.4 2. Move cursor to file menu T_P + T_M = 1.35 + 1.10 = 2.33 3. Select “save as” in file menu (click, move, click): T_M + T_K + T_P + T_K = 0.35 + 1.35 + 1.10 + 0.35 = 7.05 4. Application prompts for file name T_R = 1.2; user types 8 characters: T_R + T_M + T_K*8 + T_K for return = 1.2 + 1.35 + 0.35*8 + 1.35 + 0.35 = 7.05 Total = 13.05

  8. “Discount” Usabilty Evaluation • For the Scrooges among you … • Hybrid of empirical and heuristic 1. Make small cheap paper scenarios 2. Think aloud protocols with 1-3 users 3. Revise scenario 4. Evaluate scenario using heuristic evaluation

  9. Reporting methods • How will expert reviewers report back to you? • Unstructured • They say it however they want • Does not bias what is said • More work on your part to organize • Predefined categories • Provide checklist of problem categories • Easy to score • Inflexible; may miss observations • Structured • Compromise: they can report any problems they want but put it in structured format • More work for the reviewer

  10. Assignment • Apply heuristic evaluation or usage simulation to someone else’s project • Base it on the materials posted in Kukakuka • Put your analysis in Kukakuka

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