SIE 515 Design Rules Lecture 5

Today’s Schedule Authority vs. Generality Principles, standards, and guidelines Importance of the guidelines document Golden rules Discussion of reading Specific design principles: Learnability Flexibility Robustness

Design Rules Why give a damn about design rules? Definition of design rules: creates usable systems by restricting the state space of possibilities. Goal: Facilitate best practices when making design decisions.

Classes and Types of Rules Two classes of rules: Authority Generality Three types of rules: Principles - abstract, theory based design rules Standards - specific design rules ISO www.iso.org WAI http://www.w3.org/WAI/ Guidelines - suggestive design rules Human Engineering Data Compendium http://www.dtic.mil/dticasd/edc/TOC/EDCTOC.html World Wide Web Consortium http://www.w3.org/

Shneiderman’s 8 Golden Rules 1. Strive for consistency 2. Enable frequent users to use shortcuts 3. Offer informative feedback 4. Design dialogs to yield closure 5. Offer error prevention and simple error handling 6. Permit easy reversal of actions 7. Support internal locus of control 8. Reduce short-term memory load

Shneiderman Tree Map

Norman’s 7 Principles 1. Use both knowledge in the world and knowledge in the head. 2. Simplify the structure of tasks. 3. Make things visible: bridge the gulfs of execution and evaluation. 4. Get the mappings right. 5. Exploit the power of constraints, both natural and artificial. 6. Design for error. 7. When all else fails, standardize.

Summary of principles affecting learnability Source: Dix et al., Chap 7

Warning Panel

Summary of principles affecting flexibility Source: Dix et al., Chap 7

Summary of principles affecting robustness Source: Dix et al., Chap 7

2008 impala

Next Class Assignment 5: Task 1: Read Shneiderman Chapter 3. Task 2: Answer the following questions: What are the most important contributions of the reading? How do these factors relate to good design? Give an example. Task 3: Identify questions or issues that you would like to talk more about during class/on the participation blog.