Chapter 6 Thinking about requirements and describing them

Usability Requirements The desired qualitative or quantitative usability goals for a system Qualitative – desired goals for usability Quantitative – usability metrics UIDE Chapter 6

Early Views of Usability Learnability – time and effort required to reach a specified level of use performance Throughput – tasks accomplished by experienced users, speed, and errors Flexibility – extent to which system can accommodate changes Attitude – positive attitude of users UIDE Chapter 6

Usability The Modern-Day View of Usability 5 Es Effective Efficient Engaging Error tolerant Easy to learn UIDE Chapter 6

Constraints and Trade-offs in Relation to Requirements Gathering Costs/Budgets/Timescales Technical Constraints Trade-Offs UIDE Chapter 6

Problems with Requirements Gathering Requirements Specification User characteristics Tasks and task characteristics Environmental factors Usability Constraints and trade-offs UIDE Chapter 6

Prototyping Purposes of Prototyping: Why Bother Trying Out Your Ideas? Check feasibility of ideas with users Check usefulness of the application Allow users to contribute Allow users to test ideas Validate requirements Negotiate requirements UIDE Chapter 6

Prototyping Low-Fidelity Prototypes Sketching Screen Mockups Storyboards UIDE Chapter 6

High-Fidelity Prototypes: Using Software Tools to Try Out Your Ideas Cautions about Prototyping UIDE Chapter 6