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Quiz 2 on Thursday
Same format as the first quiz
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Planning for the Presentation
How will you use the time?
This is a presentation to the client, with the instructor and
teaching assistant as a secondary audience. Possible topics:
• Overview of project and progress against plan.
• Presentation of assumptions, decisions.
• Summary of requirements in moderate detail.
• What has been learned since feasibility study? Changes
Allow 15 minutes for questions. Expect interruptions.
"This is our understanding of your requirements."
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Planning for the Presentation
Not everybody is a great presenter, but everybody can be
Have a rehearsal, check visual aids and demonstrations.
Then change nothing.
Check out the equipment in the meeting room. What
network will you use (if any). How will you connect a
computer (if you do)? What about firewalls?
Will one person act as chair and call on other members of
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During the Presentation
• The presenter should stand. Other people should sit.
• Appoint a team member to take notes.
• The first presenter should introduce everybody.
• When asked a question:
-> If the presenter knows the answer, answer it.
-> Or the presenter may ask another team member to answer.
-> Otherwise make a note and reply later.
• Never interrupt your colleagues. If you have information
to add, raise you hand and the presenter can decide whether
to call on you.
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The Analyze/Design/Evaluate Loop
The Information Science program and Communication Department
offer a series of courses in Human Computer Interaction.
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Requirements for User Interfaces
It is very difficult to specify an interactive interface in a
• Requirement documents benefit from sketches, comparison with
existing systems, etc.
• Design documents should definitely include graphical elements
and often benefit from a mock-up or other form of prototype.
• Implementation plans should include evaluation of user factors
and time to make changes.
User interfaces must be tested with users. Expect to change
the requirements as the result of testing.
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Tools for Usability Requirements and Evaluation
Initial Mock-up Prototype Production
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Tools for Usability Requirements:
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Tools for Usability Requirements: Focus Group
A focus group is a group interview
• Potential users
Typically 5 to 12
Similar characteristics (e.g., same viewpoint)
• Structured set of questions
May show mock-ups
• Repeated with contrasting user groups
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Device-aware User Interfaces
desk-top computer, fast network connection
laptop computer, intermittent connectivity
digital camera, camcorder
Device-aware user interfaces:
=> performance of device
=> limited form factor (display, keyboard)
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Requirements about accessibility (e.g., support for users
with disabilities) are most likely to arise in the user
You may have a legal requirement to support people with
Example of requirements specification:
The system must comply with Section 508 of the US
Rehabilitation Act. See http://www.section508.gov/
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Usability: Non-Functional Requirements
Performance, Reliability, Scalability, Security…
Example: Response time
0.1 sec – the user feels that the system is reacting
1 sec – the user will notice the delay, but his/her flow of
thought stays uninterrupted
10 sec – the limit for keeping the user's attention focused on
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The Importance of User Interface Design
Good support for users is more than a cosmetic flourish
• Elegant design, appropriate functionality, & responsive system:
=> a measurable difference to their effectiveness
• A system that is hard to use:
=> users may fail to find important results,
or mis-interpret what they do find
=> user may give up in disgust
A computer system is only as good as the interface it provides to
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Design from a System Viewpoint
mental functional design
model data and metadata
computer systems and networks
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What a person thinks is true about a system, not necessarily
what is actually true
• Similar in structure to the system that is represented
• Allows a person to predict the results of his actions
• Simpler than the represented system. A mental model
includes only enough information to allow accurate
predictions (i.e. no data structures)
Also called conceptual model
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Examples of Mental Model
The mental (conceptual) model is the user's internal model
of what the system provides:
• The desk top metaphor -- files and folders
• The Web model -- one vast collection of pages with
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The interface design is the appearance on the screen and
the actual manipulation by the user
• Fonts, colors, logos, key board controls, menus, buttons
• Mouse control or keyboard control
• Conventions (e.g., "back", "help")
• Screen space utilization in Acrobat.
• Number of snippets per page in Web search.
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Principles of Interface Design
Interface design is partly an art, but there are general
• Consistency -- in appearance, controls, and function.
• Feedback -- what is the computer system doing?
why does the user see certain results?
• Users should be able to interrupt or reverse actions
• Error handling should be simple and easy to comprehend
• Skilled users should be offered shortcuts;
beginners should have simple, well-defined options
The user should feel in control
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The functional design, determines the functions that are
offered to the user
• Selection of parts of an object
• Searching a list or sorting the results
• Help information
• Manipulation of objects on a screen
• Pan or zoom
There may be many user interface choices for the same
function, e.g., Macintosh v. Windows desktop
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Data and Metadata
Structural data and metadata stored by the
computer system enable the functions and the
• Effectiveness of searching depends on the type and
quality of data that is indexed (free-text, controlled
• The desktop metaphor has the concept of associating
a file with an application. This requires a file type
to be stored with each file:
-- extension to filename (Windows and Unix)
-- resource fork (Macintosh)
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Computer Systems and Networks
The performance, reliability and predictability of computer
systems and networks is crucial to usability
• Instantaneous response time for mouse tracking and echo of
• Pipelined algorithm for the Mercury page turner
• Quality of Service for real time information
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Design: Command Line Interfaces
User interacts with computer by typing commands
• Allows complex instructions to be given to computer
• Facilitates formal methods of specification & implementation
• Skilled users can input commands quickly
• Unless very simple, requires learning or training
• Can be adapted for people with disabilities
• Can be multi-lingual
• Suitable for scripting / non-human clients
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Command Line Interfaces and
Command line interfaces and text-only menus had become
almost entirely replaced by graphical interfaces, but are
• Devices with small form factor or other special features, e.g.
cell phone, PDA, etc.
• Interfaces for simple tasks with general users, e.g. automated
bank teller (ATM)
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Design: Command Line Interfaces
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Graphical Interfaces and Direct Interaction
User interacts with computer by manipulating objects on screen
• Can be intuitive and easy to learn
• Users get immediate feedback
• Not suitable for some complex interactions
• Does not require typing skills
• Straightforward for casual users, may be slow for skilled users
• Icons can be language-independent
• Difficult to build scripts
• Only suitable for human users
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Design for Direct Manipulation
metaphors and mental models: Conceptual models,
metaphors, icons, but there may not be an intuitive model
navigation rules: How to move among data functions, activities
and roles in a large space
conventions: Familiar aspects that do not need extra training.
=> scroll bars, buttons, help systems, sliders
=> good for users, good for designers
look: characteristics of the appearance that convey information
feel: interaction techniques that provide an appealing experience
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Design for Direct Manipulation: Menus
• Easy for users to learn and use
• Certain categories of error are avoided
• Enables context-sensitive help
Major difficulty is structure of large choices
• Scrolling menus (e.g., states of USA)
• Associated control panels
• Menus plus command line
Users prefer broad and shallow to deep menu systems
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Help System Design
Help system design is difficult
• Must prototype with mixed users
• Categories of help:
=> Overview and general information
=> Specific or context information
=> Tutorials (general)
=> Cook books and wizards
=> Emergency ("I am in trouble ...")
• Must have many routes to same information
Never blame the user!
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Simple is often better than fancy
fast to compute and transmit
• Graphical interface
simple to comprehend / learn
uses of color
variations show different cases
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Separation of Presentation from Content
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Refining the Design based on Evaluation
Designers and evaluators need to work as a team
Designers are poor evaluators of their own work, but know the
requirements, constraints, and context of the design:
• Some user problems can be addressed with small changes
• Some user problems require major changes
• Some user requests (e.g., lots of options) are incompatible
with other requests (e.g., simplicity)
Do not allow evaluators to become designers
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• Iterative improvements during development.
• Making sure that a system is usable before launching it.
• Iterative improvements after launch.
• Categories of evaluation methods:
Analytical evaluation: without users
Measurements on operational systems
Empirical evaluation: with users
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How do you measure usability?
Usability comprises the following aspects:
• Effectiveness – the accuracy and completeness with which
users achieve certain goals
Measures: quality of solution, error rates
• Efficiency – the relation between the effectiveness and the
resources expended in achieving them
Measures: task completion time, learning time, clicks number
• Satisfaction – the users' comfort with and positive attitudes
towards the use of the system
Measures: attitude rating scales
From ISO 9241-11
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Evaluation based on Measurement
Basic concept: log events in the users'
interactions with a system
Examples from a Web system
• Clicks (when, where on screen, etc.)
• Navigation (from page to page)
• Keystrokes (e.g., input typed on keyboard)
• Use of help system
May be used for statistical analysis or for detailed
tracking of individual user.
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Evaluation based on Measurements
Analysis of system logs
• Which user interface options were used?
• When was was the help system used?
• What errors occurred and how often?
• Which hyperlinks were followed (click through data)?
• Complaints and praise
• Bug reports
• Requests made to customer service
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Evaluation with Users
Testing the system, not the users!
Stages of evaluation with users:
User testing is time-consuming, expensive, and essential.
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Evaluation with Users: Preparation
• Determine goals of the usability testing
“Can a user find the required information in no more than
• Write the user tasks
“Answer the question: how hot is the sun?”
• Recruit participants
Use the descriptions of users from the requirements phase
to determine categories of potential users
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Concept: monitor users while they use system
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Evaluation with Users: Sessions
• Conduct the session
– Usability Lab
– Simulated working
• Observe the user
– Human observer(s)
– Video camera
– Audio recording
• Inquire satisfaction data
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Evaluation with users:
• If possible, use statistical summaries.
• Pay close attention to areas where users
– were frustrated
– took a long time
– could not complete tasks
• Respect the data and users' responses. Do not make
excuses for designs that failed.
• Note designs that worked and make sure they are
incorporated in the final product.
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Design Tensions in Networked Systems
• Client computers and network connections vary greatly in
• Client software may run on various operating systems. It
may be current or an earlier version. What assumptions do
you make about the user's computer and Web browser?
• Designers wish to control client software, e.g., Web
browsers, but users wish to configure their own
environments. This can be a factor in accessibility, e.g.,
which part of the system determines the font size.
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Usability and Cost
• Good usability may be expensive in hardware or special
• User interface development may be a major part of a
software development project
Programming environments provide powerful user interface
• Costs are multiplied if a user interface has to be used on
different computers or migrate to different versions of
Web browsers provide a general purpose user interface where
others maintain the user interface software
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