Built-In Usability: A Usage-Centered Design Approach Chapter 2 Betty Wilkins 02/07/06

2 Topics  Interfacing with Users  Elements of a Usage-Centered Approach  Driving Models  Coordinated Activity

3 Interfacing with Users  Users (end users) Originally were not allowed near early computers Operators and service technicians (not really “users”)  Inputs/Outputs Punched cards (input) Printed reports (output)

4 Interfacing with Users  User Interface Keyboard and keypad  Betty Holberton, Jean Bartik Terminals, minicomputers Timesharing  User-centered Design Shift from technical interface to issues of the user  Usage-centered Design User-centric design (Norman, et. al) Shift to “usage”-centered focusing on the “work” to be accomplished and “how” it is accomplished

5 Elements of a Usage-Centered Approach 1.Pragmatic Design Guidelines Rules of Usability:  General character of well-defined, usable systems  Broad, overall directions for user interface design Principles  Narrower guidance on more specific issues in software usability 2.Model-driven Design Process Nature of uses of system Organization of user interface

6 Elements of a Usage-Centered Approach 3.Organized Development Processes Scaled to suit project size and scope Flexible to suit objectives and constraints 4.Iterative Improvement Successive refinements, inspections, testing 5.Measures of Quality Software metrics Augment inspections, testing

7 Driving Models Help developers to organize their thinking  Attractive Abstractions Attention on larger picture Innovation, imagination  Essentials Models Requirements apart from data structures and algorithms Capture essence of problems through abstract descriptions Highlight purpose – what & why Fewer elements and features; simpler and smaller

8 Driving Models  Architecture of Interfaces Overall structure, total organization Lead up to physical design  Multiple Views Users, their work (usage), user interface  Models Role model – role users can play Task model – tasks to accomplish Content model – tools and materials Operational model – context system is used Implementation model – visual design of interface  Generally Simple

9 Coordinated Activity  Design Activity Model – p 34  Flexible Staging Rearranged, expanded, compressed, omitted  Order and Chaos Feed-forward/work-back Deferred decisions

10 Summary  Interfacing with Users  Elements of a Usage-Centered Approach  Driving Models  Coordinated Activity