CS 5150 Software Engineering Lecture 11 Usability 2

CS Administrivia Feasibility studies Surveys canceled Anonymous feedback Team feedback

CS First Presentation Contents Motivation, Scope & Goals Quick -- no more than a few minutes DO NOT assume your audience read the feasibility study Progress to date Whatever you’ve done... Detailed requirements, mock-ups, prototypes, system architecture Schedule & Plan How are you doing relative to your plan in your feasibility report? Revised plan

CS SE in the News Recent history of patents in America changed dramatically in 1982 One appeals court took over a lot of power Crazy stat: Microsoft patents received in s:5; 1990s:1,116; 2000s:12,330 Fitocracy: Will every UI become a game?

CS Interface Design Most human interaction with software now is some kind of GUI Windows desktop, tablet, etc Relatively easy to learn and discoverable Support tight feedback loop Hard to automate tasks

CS Design for Direct Manipulation Visual components are “actors” that have state and can be manipulated independently Conflict with usual programming language focus on procedures metaphors and mental models: Conceptual models, metaphors, icons; may or may not be intuitive “Navigation” in a conceptual space can engage spatial reasoning Use existing conventions whenever you can look: Appearance idioms that convey meaning feel: User input and feedback idioms

CS Design Elements: Menus Pros: Easy for users to learn and use Certain categories of error are avoided Enables context-sensitive help Challenges: Scrolling menus (e.g., states of USA) Hierarchical Associated control panels Menus plus command line Users prefer broad and shallow to deep menu systems

CS Help System Design Help system design is harder than many programmers assume Must test with inexperienced users Kinds of help systems: Manual Context information Tutorials Cook books & wizards Emergency Must have many routes to help information Never blame the user

CS Information Presentation Simple is often preferable to pretty Text precise, unambiguous fast to manipulate and transmit Graphical interface Can be easier to learn colors and animation can convey information

CS Separation of Content from Presentation

CS Remember the Mantra: Design and Evaluate

CS Evaluations Quick, cheap iteration when you’re exploring a new interface idea (early stage development) Test usability with real users before launch/deployment (late stage development) Continue refining with user feedback after launch/deployment (maintenance) Categories of evaluation: Informal testing Expert review Measurement on the actual system Empirical evaluation with users

CS Measuring Usability Effectiveness Can the users complete their goals (accurately) with the software Efficiency Effectiveness per unit time/effort Satisfaction Subjective evaluation of how pleasing or easy the interface is

CS Evaluation based on Measurement Basic concept: log events in the users' interactions with a system Examples from a Web system Clicks (when, where on screen, etc.) Navigation (from page to page) Keystrokes (e.g., input typed on keyboard) Use of help system Errors May be used for statistical analysis or for detailed tracking of individual user

CS Sometimes Called Metrics Analysis of system logs Which user interface options were used? When was was the help system used? What errors occurred and how often? Which hyperlinks were followed (click through data)? Human feedback Complaints and praise Bug reports Requests made to customer service

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CS Evaluation with Users “Test the system, not the user” Prepare, evaluate, analyze Preparation Decide on goals (what activities do you want to test?) Write user tasks Recruit participants

CS Usability Lab

CS User Observation Considerations Is environment realistic? Record Video, audio, I/O actions Standardized feedback

CS Analyzing User Test Results Pay close attention to Any frustrations Long pauses Incomplete tasks Resist impulse to blame users Statistics can be useful, but most users studies aren’t large enough to justify strong statistical conclusions

CS Evaluation Example: Eye Tracking

CS Good for Complex UIs

CS Refining Designs Critical to keep the roles of designer and evaluator separate Designers tend to assume their existing designs are good enough too quickly Evaluators do not understand the constraints of the project as well Negotiation is key!

CS UI Design Tension: Control of Appearance Does the designer control the UI down to the pixel level? Not practical in modern web apps Can be important in modern mobile apps Supporting multiple platforms well can be expensive

CS Usability and Cost Cost increases dramatically with degree of UI innovation Use a multi-tier user testing strategy office mate, expert review, small external testing Testing is hard to automate Releasing hard-to-use software can be fatal