Computer/Human InteractionLecture 39Overview:Usability Engineering in PracticeCost-Benefit AnalysisInternationalization and LocalizationEthical/Social IssuesAssignment: Homework 6 out, due Friday as part of Exam 2 ReviewUsability Engineering in PracticeWhat kind of job might a usability expert encounter?In 1970's, it was common to schedule user tests at end of development for client acceptance. Results of tests:Cosmetic improvementsCalls for additional trainingRequirements for future versionsUsability Engineering in 1980sIn 1980's, competition and faster product cycles pushed usability testing earlier into development. Two approaches.Separate usability groups that act as general resource to multiple development teams+ resource sharing, cross-product insights, organizational learning- communication overhead, time-sharing, prioritization Usability Engineering in 1980s 2Integrate usability specialist as part of each development team+ tightly integrated, focused work, appreciation of project-specific constraints- less objectivity, hard to generalize+ increases likelihood that right use-related questions will be raised and addressed, immersion in problem domain- many companies cannot or will not afford to employ enough specialists to cover each projectUsability Engineering NowUsability engineers work with requirements specification along with marketing as well as in design.HCI identified as a core area within CS, so most CS graduates have some exposure to HCI conceptsHCI research and graduate programs. E.g., Ph.D. - CMU, Georgia Tech, Stanford; M.S. - DePaul, IUCost-Benefit AnalysisCosts - enumerate usability activitiesWriting development scenarios, includes field work, interviews, surveys, etc., and analysisRefining and reviewing scenariosDeveloping prototypes: paper, running walkthroughs, analysisFormative evaluation and analysisTest labTravel, if no co-located with developersGenerally, will it delay developmentCost-Benefit Analysis 2Benefits - hard to estimate, some positive outcomes usually attributed to usability engineeringfewer downstream changes; studies estimate that a change at prototype stage is 25% of cost of a change after installation. E.g., if assume 5 design changes of 4-8 hours to effect, then saves a week of effort.reduced training and customer supportCost-Benefit Analysis 3More attributed benefitsincreased user productivity; e.g., predict typical user performance if save .5 minutes per 20 interactions per day, every day of product life; similarly with error recoverycustomer loyalty, both repeat purchase and referralsincreased salesExample in textbook (Table 10.1, p 348): $68K cost, $6.8M projected savingsInternationalization and LocalizationCompany can minimize costs by providing only one interface, but not a good ideaWorld is less interesting if all the sameCulture is like workplace environment and should be one of the contexts of use. E.g., terms like “kill” might be offensive; using picture of dog for fetch; colors; date formatsInterface standards can help with thisLocalization is design strategy that supports systematic variation among regions and culturesEthical/Social IssuesSafety - e.g., Therac-25 radiation therapy machineBad engineering with bad interfaceSafety interlock was removed because assumed can find all software errorsAdded complexity without documentationInterface was not synchronized with internal state; error messages were not specific (same one for both too high and too low)No separate testing before put into use6 people died of massive radiation burnsEthical/Social Issues 2Digital DivideHaves vs. have nots; functionally illiterate now includes computer useSpecial needs; can drive improvements for all usersHead-mounted pointing device for hands-free operationVisual enlargement for elderlyAudio enhancements for noisy environmentsElderly are the fastest growing segment of users, need more robust, simpler designsHomework 6In textbook: Exercise 2 on page 301, Exercise 1 on page 339, Exercise 1 on page 360Due at beginning of class on Friday as part of Exam 2