Interface Types and ModelsInteraction designBasic activities of interaction design projectsLife cycle modelsSlide 5Waterfall lifecycleWaterfall modelSpiral lifecycleRapid Application Development (RAD)Key features of RAD projectsRAD phasesStar lifecycleUsability engineering lifecycleUsability engineering basicsRequirements: A definitionWho are your users?Finding out about your usersGroup Class ActivityNext individual/group assignment tentative descriptionInterface Types and Models Dr. Dania BilalIS 588 Spring 2008Interaction design•Focuses on designing and building interactive products•How to accomplish User-Centered Design•User rather than system concerns to guide the development process•Requires the work of a teamBasic activities of interaction design projects1. Identify needs and establish user requirements 2. Develop alternative designs 3. Conceptual designs/model•Physical designs/product detail4. Build interactive prototypes 5. EvaluationLife cycle models•Show how activities fit together–Limited by resources•Provide a framework for managing projects•Simple model •See Text, fig. 9.7, p. 448.Life cycle models•Software engineering–Waterfall–Spiral–Rapid Application Development (RAD)•HCI –Star Lifecycle–Usability EngineeringWaterfall lifecycle•First generally used life cycle model for software development•Originally proposed in the 1970’s•Linear model•5 stages•User involvement not built into the model (see fig. 9.8, p. 450).Waterfall model•Some level of iteration•Requirements are frozen while design and implementation are completed•Problem–Iteration around each stage and previous but not all over –No account for change over time –Lacks an explicit role for user involvementSpiral lifecycle•Created by Barry Boehm in 1988•Integrate risk analysis & prototyping into the model•Results in the inclusion of iterative testing of alternatives appropriate to each given stage•See fig., 9.9, p. 451.Rapid Application Development (RAD)•Developed in the 1990’s in response to pressure to include user focus•Goal: minimize the risk of changing the requirements over time•Non-linear•Iterative process•See fig. 9.10, p. 452Key features of RAD projects •Time boxes–Time limited cycles (about 6 months)–Breaks a large project into smaller projects–Deliver incrementally–Enhance flexibility•Joint Application Development (JAD) “workshops”–Users and developers thrash out requirements–stakeholder groups are involved in designRAD phases•Project initiation•JAD workshops•Design and build (iterative)•Evaluation of final system•Review implementationStar lifecycle•Developed from research on interface designers•Distinguishes analytical & synthetic modes of working•Model suggests activity can begin at any point IF it flows through evaluation•See fig. 9.15, p. 459.Usability engineering lifecycle •Beginnings:– Whiteside, Bennett & Holtzblatt at DEC in 1988–Nielsen at Bellcore 1992•Deborah Mayhew’s textbook (1999)–Detailed specification for how to do usability engineering–How to integrate usability testing into the product lifecycleUsability engineering basics•Set usability goals as part of system specification•Goals must be quantitative•Measures may include –Behaviors•Time to complete task, % task completion, number/percent errors, number of commands, etc.–Attitudes•User preference, user satisfaction, etc.Requirements: A definition•“Statements about an intended product that specifies what it should do or how it should perform”•Types–Functional–Non-functional•Serve as constraints•Include: data requirements, environmental constraints (physical, social, organizational and technical)Who are your users?•Stakeholders•Types of users (Eason, 1987)–Primary•Frequent, hands-on–Secondary•Occasional users–Tertiary •Affected by system introduction•May have purchase power over systemFinding out about your users•Chapters 8,7,10–Data gathering methods–Choosing among methods–Data interpretation and analysis–Tasks description–Task analysisGroup Class Activity•You are developing a digital repository for an agency (select an information agency or a library of your choice)•The depository will include digitizing a specific collection and designing a system to provide access to the collection.•How will you begin and what model will you use?Next individual/group assignmenttentative description•Think of a product you want to design.•Product should be of common interest to you and the group you will work with•What do you want the product to do for you?•Find 5 potential users of the product and interview them about the product (what are their requirements?)•Write a list of requirements based on the information you gathered.•Meet with the team, discuss the requirements you collected, refine the requirements and generate a comprehensive list of these requirements (from all team members).•Identify and describe the requirements that are feasible for feeding into the interaction design of the product and justify why.•Find similar products and evaluate their design vis-à-vis the requirements you collected.•Sketch some initial design for the product.•Sketch alternative design for the product.•Evaluate the two designs with “real users” based on usability criteria and user experience goals.•Reiterate the design based on the results of the usability criteria and user experience goals•Write a final