Gebruikersaspecten van software systemen User Aspects of Software Systems

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

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.

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

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

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

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

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

Chapter 1 Introduction

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

1.1 Illustrating Example

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

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

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

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

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

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)

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

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

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

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

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

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

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 9241-11)

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

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

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

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)

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

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

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

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

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

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

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

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