1. Gebruikersaspecten van software systemen
User Aspects of Software Systems

2. Books:
[1] “User-Centered Website Development. A Human-Computer Interaction Approach”, D.D. McCracken, R.J. Wolfe, Pearson Prentice Hall, 2004.
[2] “Model-Based Design and Evaluation of Interactive Applications”, F. Paternò, Springer, 2000.
[3] “Graphical User Interface Design and Evaluation”,
Redmon-Pyle and Moore, Prentice-Hall, 1995
WebSite: via elvas or via wise.vub.ac.be

3. What is this course about?
How to make a good (= usable) user interface for an interactive application
Why are usable user interfaces important?
Nearly all applications have a user interface
Bad interfaces are frustrating for the user and will influence the productivity
Competitors may have better systems
Good user interface are hardly noticed, bad ones are!
It is easier to make a bad interface than a good one.

4. Content (1) Introduction Capabilities of the Human Being
Usability: Illustrating example
HCI overview
User-Centered Development Methodology
Capabilities of the Human Being

5. Content (2) The User Interface Design Process
3.1 The Users and their Usability Requirements
3.2 Task Analysis & Task Modeling
3.3 User Object Modeling
3.4 The Style Guide
3.5 Design
Task-Driven Design
Visual Organization
Use of Color
Typography
Multimedia
3.6 Prototyping
3.7 Evaluation

6. Content (3) Accessibility Localization
Model-Based Approaches for UI design
 GOMS
 Norman’s cycle
 Task analysis methods
 UAN
 Petri Nets
 UML
More details on the website

7. Format of the Course Chapter 6 Rest (Methodology) Project in groups
Self-study
Rest (Methodology)
During the lessons
Project in groups

8. Good Design is as easy as 1-2-3
Learn the principles They are simpler than you might think
Recognize when you are not using them Put into words - name the problems
Apply the principles you will be amazed

9. Chapter 1 Introduction

10. 1. Introduction Content Usability: Illustrating example
The history and goals of Human-Computer Interaction
The methodology of User-Centered Development

11. 1.1 Illustrating Example

12. It doesn’t have to be that way
You can design user interfaces that
Are pleasant and convenient for your users
Let them accomplish their goals
The key: think about your users
Learn about them
Watch them work, in their workplace
Interview them, also in their workplace

13. Benefits of Usable User Interfaces
Gaining a competitive edge
Reducing development and maintenance costs
Improving productivity
Lowering support costs

14. Reducing development and maintenance costs
Learn about users first, and you will avoid
Implementing features users don’t want
Creating features that are annoying or inefficient
High cost of making changes late in the development cycle

15. Improving productivity
Productivity means employees become more efficient because the system supports their tasks in an easy way.

16. Lower support costs
Calls to customer support are very expensive for the vendor: estimates range from €12 to €250 per call

17. 1.2 What is HCI?
“Human Computer Interaction is a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of the major phenomena surrounding them.”
As defined by the Special Interest Group on Human-Computer Interaction (SIGCHI) of the Association for Computing Machinery (ACM)

18. A major shift
50 years ago the cost of a computer would pay the salaries of 200 programmers for a year
Today the salary of one programmer for a year will buy 200 computers—each vastly more powerful than the early machines
Late 70’s: smaller and cheaper computers (PC’s) used by non-computer experts
Now the goal is to make computers easy to use, to save people time

19. Examples of interactive computing systems
Single PC - capable of displaying web pages
Embedded devices, for example in cars and in cell phones
Handheld Global Positioning Systems for outdoor activities

20. 1.3 Goals of HCI To develop or improve the Safety Utility
Effectiveness
Efficiency
Usability
Appeal
of systems that include computers

21. Safety Safety of Users—think of Safety of Data—think of
Air traffic control
Hospital intensive care
Safety of Data—think of
Protection of files from tampering
Privacy and security

22. Utility and effectiveness
Utility: what services a system provides e.g. Ability to print documents
Effectiveness: user’s ability to achieve goals, e.g.
How to enter the desired information
How to print a report
Utility and effectiveness are distinct
A system might provide all necessary services, but if users can’t find the services items, the system lacks effectiveness

23. Efficiency
A measure of how quickly users can accomplish their goals or finish their work using the system

24. Usability Definitions
“a measure of the ease with which a system can be learned and used, its safety, effectiveness and efficiency, and attitude of its users towards it” (Preece et al., 1994)
“the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use” (ISO )

25. Usability (2) Ease of learning ! Ease of use ! Appeal/ attitude !
How well users like the system
First impressions
Long-term satisfaction

26. How can we measure usability?
How can we develop a system to ensure usability?
Paradigms
Usually based on new technology
E.g. WIMP interface
Principles
Independent of technology

27. Principles to support usability
Learnability
The ease with which new users can use the system effectively
Flexibility
The multiplicity of ways the user and the system exchange information
Effectiveness
the level of support provided to the user to achieve successfully its goals

28. Learnability Principles affecting learnability: Advantages
Predictability: to be able to predict the result of an interaction
Feedback: the system provides feedback about the effect of the interaction
Familiarity: correlation between the user’s existing knowledge and the knowledge required to use the interaction
Generalization: e.g. drawing rectangle will be the same as drawing square; close/open window will be the same as in other MS word application
Consistency: in naming, color use, command invocation, …
Advantages
reduces training time and costs
enable more flexible staffing practices (staff become effective more quickly)

29. Flexibility (1) Examples: Input/output in different forms
Inches/cm, fixed point/decimal, % or fixed part, …
Input may be output and vice versa:
Draw line, out: coordinates
Give coordinates, out: draw line
Order of tasks is not fixed
System driven interaction hinders flexibility, user-driven interaction favors it
Multi-treading allows to support more than one task at the time

30. Flexibility (2) Related: Customization:
Adaptability: user can adapt the user interface
Adaptivity: The user interface can be adapted by the system
Personalization: user interface is tailored towards the individual user
Advantages
allows reorganization of tasks and business

31. Effectiveness
Always for a specified range of tasks and group of users in a particular environment.
Principles affecting effectiveness:
Ability to observe the internal state of the system
Ability to take corrective actions once an error has been recognized
Response time
Task completeness: are all user tasks supported by the system?
Task adequacy: match of the task as understood by the user and supported by the system
Advantages:
higher productivity

32. 1.4 User-Centered Development Methodology
Traditional software engineering methods arose in 1960s and 1970s
Systems were not highly interactive
End-user were computer specialists
Issues concerning end-user and usability were not at all important
user interface design not considered explicitly
Now:
Most end-users are not computer specialists
Usability vital for success

33. Traditional System-Centered design:
Emphasis on the functionality,
UI is added at the end
Emphasis on correct software rather than on ease of use
User has to adapt himself to the system
Things are changing: User-Centered design
UI more important
Emphasis on end-users’ tasks,
Early end-user participation: in analysis and design
Evaluation by end-users
Consequences:
more work for UI-designer and UI-programmer

34. Summary: User Centered Development User-centric, not data-centric
Involves users in the design process
Usability can be quantified and measured
Highly Iterative
Involves testing and revision
Interdisciplinary, building on a dozen different disciplines

35. Fields that HCI builds on (1)
Computer Science
Implementation of software
Engineering
Faster, cheaper equipment
Ergonomics
Design for human factors
Graphic design
Visual communication
Technical writing
Textual communication

36. Fields that HCI builds on (2)
Linguistics, artificial intelligence
Speech recognition, natural language processing
Cognitive psychology
Perception, memory, mental models
Sociology
How people interact in groups
Anthropology
Study of people in their work settings