1.3 System - User Interface Design Goals

• Define the target user community associated with the interface
• Communities evolve and change
• 5 human factors central to community evaluation:
1. Time to learn

How long does it take for typical members of the community to learn relevant task?
2. Speed of performance

How long does it take to perform relevant benchmarks?
3. Rate of errors by users

How many and what kinds of errors are commonly made during typical applications?
4. Retention over time

Frequency of use and ease of learning help make for better user retention
5. Subjective satisfaction

Allow for user feedback via interviews, free-form comments and satisfaction scales.
• Trade-offs sometimes must be allowed in development, use tools such as macros and shortcuts to ease some burdens
• Test all design alternatives using a wide range of mock-ups