A Practical Introduction
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************************************************************* ** * TASK-CENTERED USER INTERFACE DESIGN * ** * A Practical Introduction * ** ** * Clayton Lewis * * John Rieman * ** ************************************************************* -------------------------------------------------------- | SHAREWARE NOTICE: | | | | The suggested shareware fee for this book is $5.00, | | payable to Clayton Lewis and John Rieman. Send it to: | | | | Clayton Lewis and John Rieman | | P.O.Box 1543 | | Boulder, CO 80306 USA. | | | | If sending U.S. dollars is difficult, for example if | | you aren’t in the U.S., send us something else you | | think we’d like to have. Or send us two somethings, | | one for each of us. | | | | COPYRIGHT INFORMATION | | | | This book is copyright 1993, 1994 by Clayton Lewis and | | John Rieman. You are free to make and distribute | | copies of the book in electronic or paper form, with | | the following restrictions: (1) We ask that you pay | | the shareware fee if you find the book useful and if | | you can afford it. (2) Every copy must include this | | "shareware notice." (3) Copies must be unchanged from | | the original. (4) No part of the book may be sold or | | included as part of a package for sale without the | | authors’ written permission. | | | | Original files for the book are available via | | anonymous ftp from ftp.cs.colorado.edu. | | | | We thank you for your support! | | | -------------------------------------------------------- Task-Centered User Interface Design iii **************************** v.1 * * Table of Contents * * Foreword Chapter 1. Task-Centered Design Chapter 2. Getting to Know Users and Their Tasks Chapter 3. Creating the Initial Design Chapter 4. Evaluating the Design Without Users Chapter 5. Testing the Design With Users Chapter 6. User Interface Management and Prototyping Systems Chapter 7. The Extended Interface Appendix L. What Can You Borrow? Appendix M. Managing User Interface Development Exercises Text c 1993, 1994 by Clayton Lewis and John Rieman. iv Task-Centered User Interface Design Contents List of HyperTopics ix List of Examples x List of Tables xi Forward xiii 0.1 What’s This Book All About? . xiii 0.1.1 Who Should Be Reading the Book? . xiii 0.1.2 What Is the User Interface? . xiii 0.1.3 What Kind of User Interfaces Does This Book Cover? xiv 0.1.4 Why Focus on Design? . xiv 0.2 How to Use This Book . xv 0.2.1 HyperTopics and Examples . xvi 0.2.2 Exercises . xvi 0.3 About Shareware: How to Get and Pay for This Book . xvii 0.3.1 Why Shareware? . xviii 0.3.2 Special Note to Instructors and Students . xviii 0.3.3 Where to Get Up-To-Date Copies . xviii 0.3.4 Corrections and Additions . xix 0.3.5 Let Us Know What You Think . xix 0.4 About the Authors . xix 0.5 Acknowledgements . xix 0.6 Disclaimers . xx 1 The Task-Centered Design Process 1 1.1 Figure Out Who’s Going to Use the System to Do What . 1 1.2 Choose Representative Tasks for Task-Centered Design . 2 1.3 Plagiarize . 3 1.4 Rough Out the Design . 4 1.5 Think About It . 4 1.6 Create a Mock-Up or Prototype . 5 1.7 Test the Design With Users . 6 1.8 Iterate . 6 1.9 Build the Design . 7 1.10 Track the Design . 7 1.11 Change the Design . 7 Task-Oriented vs. Waterfall Design . 8 Text available from hURL:ftp://ftp.cs.colorado.edu/pub/cs/distribs/clewis/HCI-Design-Book/i. Task-Centered User Interface Design v The Design Team . 8 Responsibility . 9 Usability Objectives . 9 2 Getting to Know Users and Their Tasks 11 2.1 Getting in Touch With Users . 12 2.2 Learning About the Users’ Tasks . 13 2.3 Using the Tasks in Design . 20 Requirements Analysis . 23 Specification . 24 Planning, Design, and Beyond . 24 3 Creating the Initial Design 27 3.1 Working Within Existing Interface Frameworks . 28 3.2 Making Use of Existing Applications . 29 3.3 Copying Interaction Techniques From Other Systems . 30 Geometrical and Movement Arguments . 32 Memory Arguments . 33 Problem-Solving Arguments . 33 Attention Arguments . 33 Convention arguments . 33 Diversity Arguments . 34 3.4 When You Need to Invent . 36 3.5 Graphic Design Principles . 37 4 Evaluating the Design Without Users 41 4.1 Cognitive Walkthroughs . 46 4.1.1 Who should do a walkthrough, and when? . 48 4.1.2 What’s needed before you can do a walkthrough? . 48 4.1.3 What should you look for during the walkthrough? . 49 4.1.4 What do you do with the results of the walkthrough? 52 Summary . 53 4.2 Action Analysis . 54 4.2.1 Formal Action Analysis . 55 Points Raised by the Analysis . 60 Summary . 61 4.2.2 Back-of-the-Envelope Action Analysis . 62 4.3 Heuristic Analysis . 67 Summary . 72 4.4 Chapter Summary and Discussion . 74 Text available from hURL:ftp://ftp.cs.colorado.edu/pub/cs/distribs/clewis/HCI-Design-Book/i. vi Task-Centered User Interface Design 5 Testing The Design With Users 77 5.1 Choosing Users to Test . 77 5.2 Selecting Tasks for Testing . 79 5.3 Providing a System for Test Users to Use . 80 5.4 Deciding What Data to Collect . 82 5.5 The Thinking Aloud Method . 83 5.5.1 Instructions . 84 5.5.2 The Role of the Observer . 84 5.5.3 Recording . 85 5.5.4 Summarizing the Data . 86 5.5.5 Using the Results . 86 5.6 Measuring Bottom-Line Usability . 88 5.6.1 Analyzing the Bottom-Line Numbers . 89 5.6.2 Comparing Two Design Alternatives . 92 5.7 Details of Setting Up a Usability Study . 93 5.7.1 Choosing the Order of Test Tasks . 93 5.7.2 Training Test Users . 94 5.7.3 The Pilot Study . 94 5.7.4 What If Someone Doesn’t Complete a Task? . 94 5.7.5 Keeping Variability Down . 94 5.7.6 Debriefing Test Users . 95 6 User Interface Management and Prototyping Systems 97 6.1 Concepts . 98 6.1.1 Object-Oriented Programming . 98 6.1.2 Event-Driven Programs . 99 6.1.3 Resources . 100 6.1.4 Interapplication Communication . 100 6.2 OSF/Motif in X-Windows — Toolboxes in the Trenches . 101 6.3 Rapid Prototyping in HyperCard . 103 6.4 Windows, the Shared-Code Approach, and Visual Basic . 107 Features To Watch For . 110 Action Logging . 110 Big Program Support . 111 Code Generation . 111 Extensibility of the Interface . 111 Extensibility of the Program . 111 4GL programming . 111 Operating-System Specific Techniques . 111 Prototype to Final Application Capability . 112 Text available from hURL:ftp://ftp.cs.colorado.edu/pub/cs/distribs/clewis/HCI-Design-Book/i. Task-Centered User Interface Design vii Stand-alone Application Generation . 112 Style Guide Support . 112 Vendor Support and Longevity . 112 Visual Programming With Structure . 112 Where To Find Out More . 112 7 The Extended Interface 115 7.1 Manuals . 116 7.1.1 The Detailed Task Instructions . 118 7.1.2 The Command Reference . 122 7.1.3 The Super Index . 123 7.2 On-Line Help . 125 7.3 Training . 127 7.4 Customer-Support Phone Lines . 130 L What Can You Borrow? A Quick Introduction to Copy- rights and Related Legal Stuff, as of 1994 133 L.1 Background . 133 L.2 What’s Covered by Copyright . 135 L.3 Practical Boundary Markers . 136 L.4 Strategy . 138 L.5 Some Philosophical Observations . 138 M Managing User Interface Development 141 M.1 Staffing . 141 M.2 Organization . 142 M.3 Resource Allocation . 145 M.4 Product Updates . 149 Excercises 151 Forward . 152 0.1 Looking for the Interface . 152 Chapter 1. Task-Centered Design . 153 1.1: Task-Centered Design in Other Areas . 153 Chapter 2. Getting to Know Users and Their Tasks. 154 2.1: Task and User Analysis . 154 Chapter 3. Creating the Initial Design . 156 3.1: Selecting Controls . 156 3.2: Borrowed Colors . 156 3.3: Unpacking a Metahphor . 157 Text available from hURL:ftp://ftp.cs.colorado.edu/pub/cs/distribs/clewis/HCI-Design-Book/i. viii Task-Centered User Interface Design Chapter 4. Evaluating the Design Without Users . ..