User Interface Design and Ergonomics - National Open University of ...

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MODULE 4 UNIT 1 TECHNIQUES FOR EVALUATING AND MEASURING INTERFACE USABILITY Table of Contents 1.0 Introduction 2.0 Objectives 3.0 Main Content 3.1 Usability Evaluation methods 3.2 Evaluation with tests and metric 4.0 Conclusion 5.0 Summary 6.0 Tutor Marked Assignment 7.0 Further Reading and Other Resources 1.0 INTRODUCTION This unit describes usability evaluation methods. Cognitive modeling, Inspection, Inquiry and prototyping methods and Inspection methods are described in detail. Evaluation metrics are also discussed. 2.0 OBJECTIVES By the end this unit, you should be able to: Explain generally various usability evaluation methods. Explain the differences between these various methods. Describe evaluation metrics. 3.0 MAIN CONTENT 3.1 USABILITY EVALUATION METHODS There are a variety of methods currently used to evaluate usability. Certain methods make use of data gathered from users, while others rely on usability experts. There are usability evaluation methods that apply to all stages of design and development, from product definition to final design modifications. When choosing a method you must consider the cost, time constraints, and appropriateness of the method. For a brief overview of methods, see Comparison of usability evaluation methods or continue reading below. Usability methods can be further classified into the following subcategories: 154
3.1.1 COGNITIVE MODELING METHODS Cognitive modeling involves creating a computational model to estimate how long it takes people to perform a given task. Models are based on psychological principles and experimental studies to determine times for cognitive processing and motor movements. Cognitive models can be used to improve user interfaces or predict problem errors and pitfalls during the design process. A few examples of cognitive models include: a. Parallel Design With parallel design, several people create an initial design from the same set of requirements. Each person works independently, and when finished, shares his/her concepts with the group. The design team considers each solution, and each designer uses the best ideas to further improve their own solution. This process helps to generate many different, diverse ideas and ensures that the best ideas from each design are integrated into the final concept. This process can be repeated several times until the team is satisfied with the final concept. b. GOMS GOMS is an acronym that stands for Goals, Operator, Methods, and Selection Rules. It is a family of techniques that analyzes the user complexity of interactive systems. Goals are what the user has to accomplish. An operator is an action performed in service of a goal. A method is a sequence of operators that accomplish a goal. Selection rules specify which method should be used to satisfy a given goal, based on the context. c. Human Processor Model Sometimes it is useful to break a task down and analyze each individual aspect separately. This allows the tester to locate specific areas for improvement. To do this, it is necessary to understand how the human brain processes information. This has been fully described in Module 1. d. Keystroke level modelling Keystroke level modeling is essentially a less comprehensive version of GOMS that makes simplifying assumptions in order to reduce calculation time and complexity. You can read more about Keystroke level model for more information. 3.1.2 INSPECTION METHODS These usability evaluation methods involve observation of users by an experimenter, or the testing and evaluation of a program by an expert reviewer. They provide more quantitative data as tasks can be timed and recorded. 155
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] NATIONAL OPEN UNIVERSITY OF NIGER
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National Open University of Nigeria
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Summary ...........................
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UNIT 3 - GRAPHICAL USER INTERFACE (
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Assignments File Tutor-Marked Assig
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2 DESIGN and DESIGNING GOOD USER IN
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need both the study unit you are wo
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CIT 711: USER INTERFACE DESIGN AND
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UNIT 1 FUNDAMENTALS OF USER INTERFA
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3.3 TYPES OF USER INTERFACES Curren
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3.5 USER INTERFACE MODALITIES AND M
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Table of Contents 1.0 Introduction
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3.1.1 DESIGNING A GOOD USER INTERFA
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widgets properly is to read and und
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Figure 1:- Showing that alignment o
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6.0 TUTOR MARKED ASSIGNMENT a. How
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A graphical user interface is a typ
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Operating System. It is easy for a
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A list of items from which to selec
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collaborative work. For example, sc
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MODULE 1 UNIT 4 HUMAN COMPUTER INTE
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3.3 DIFFERNCES WITH RELATED FIELDS
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window blinds to automobile braking
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Wickens, Christopher D., John D. Le
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The International Ergonomics Associ
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approach, the Gilbreths reduced the
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3.6 BENEFITS OF ERGONOMICS The thre
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Another key to reducing lumbar disc
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MODULE 2 - USER INTERFACE DESIGN TE
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methods include inspection methods,
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Determine time of each operation (b
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unable to understand new informatio
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M cones, or, misleadingly, green co
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Motor skill which is a learned seri
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MODULE 2 UNIT 2 UNDERSTANDING USERS
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The users of a system must be ident
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This example brings up an important
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whether you want to have a palette
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Task analysis which includes identi
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MODULE 2 UNIT 3 USER CENTERED DESIG
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or small body text is also hard to
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Introduction to User-centered desig
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organizations themselves. Interacti
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After thorough analysis using vario
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Interaction design which is the dis
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In human-computer interaction and c
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The preferred method for ensuring u
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3.4 ISO STANDARDS FOR USABILITY ISO
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In this unit, you have been introdu
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affect the way the command is execu
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• Guides the user via the predefi
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Page 110 and 111: UNIT 1 PROTOTYPING Table of Content
Page 112 and 113: Figure 12: The iterative steps of p
Page 114 and 115: select print Figure 13: An interfac
Page 116 and 117: Ambler, S.W. & Constantine, L.L. (2
Page 118 and 119: 3.2 LOW-FIDELITY PROTOTYPES Low-fid
Page 120 and 121: Figure 14:- Example of Sketching II
Page 122 and 123: Much more important for features th
Page 124 and 125: DENIM, an extension of SILK, is a t
Page 126 and 127: • Encourage menu & forms style, r
Page 128 and 129: Another problem is that native widg
Page 130 and 131: interfaces, so that a realistic sim
Page 132 and 133: UNIT 3 INPUT AND OUTPUT MODELS Tabl
Page 134 and 135: Recall that perceptual fusion means
Page 136 and 137: 3.2 OUTPUT MODEL There are basicall
Page 138 and 139: directly-mapped pixel image will no
Page 140 and 141: Most stroke models also include som
Page 142 and 143: UNIT 4 MODEL VIEW-CONTROLLER (MVC)
Page 144 and 145: 3.3.2 AS A DESIGN PATTERN MVC enco
Page 146 and 147: The Views are XForms controls for s
Page 148 and 149: UNIT 5 LAYOUTS AND CONSTRAINTS Tabl
Page 150 and 151: 3.5 CONSTRAINTS Constraints are rel
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Page 156 and 157: a. Card Sorting Card sorting is a w
Page 158 and 159: Rapid prototyping is a method used
Page 160 and 161: 3.2.1 THE USE OF PROTOTYPES It is o
Page 162 and 163: Dumas, J.S. and Redish, J.C. (1999)
Page 164 and 165: the users' respect for you as a pro
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Page 168 and 169: speed whenever the average load was
Page 170 and 171: Table 4:- Table: Average times for
Page 172 and 173: phases: list the actions, and then
Page 174 and 175: Nielsen and Molich used their own e
Page 176 and 177: 7.0 REFERENCES AND FURTHER READING
Page 178 and 179: users. If you do not, you can be ba
Page 180 and 181: If you are led to develop more and
Page 182 and 183: It's very easy to shape the comment
Page 184 and 185: a. Analyzing the Bottom-Line Number
Page 186 and 187: you use. But then you need some way
Page 188 and 189: ecruit test users with more similar
Page 190 and 191: MODULE 4 UNIT 4 OTHER EVALUATION IS
Page 192 and 193: 3.2 CURRENT ISSUES CONCERNING EVALU
Page 194 and 195: 2.0 OBJECTIVES By the end this unit
Page 196 and 197: It provides a real focal point for
Page 198 and 199: 3.3.4 CONDUCTING THE TEST Having co
Page 200: The stages involved in usability te
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