Transcript Usability: Measuring the Success of the Web

Usability: Measuring the Success of the
Web-Based Delivery of Library Resources
and Services
• What is usability?
• What are the Tools and Techniques of
Usability?
• What Understandings Have Evolved?
Usability conveys a variety of
meanings
• Arose in the documentation design and
software development arenas
• Web Usability fairly new
– Page level
– Site level
• Usability engineering
• Usability analysis or inspection
• Usability testing
How does usability differ from
HCI and UCD?
• Human Computer Interaction
• User-Centered Design
• Usability
– emphasizes cost-effective methods
– more formulaic, step-by-step guidance
– less theory driven, often follows a “good enough”
goal
– intended for less technical systems
developers/managers
Stages of the Usability
Engineering Lifecycle Approach
• Know the user (cardinal rule)
– User characteristics, task and needs analysis
– User and use environment/job/office environment
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Parallel design approach
Participatory, iterative design approach
Early tests w/ heuristic analysis
Rapid Prototyping
Empirical and iterative testing, n=5 to 15
Feedback from field use
Usability Tools for Looking at the
User’s Tasks/Needs
• Create a Task Analysis - Interrelationships
• Conduct a Contextual Task Analysis - Trigger,
Scenario/Sequence, Problems
• Cognitive Walk-Throughs using Task Scenario
• Card Sort Exercises
• Heuristic Analysis using Subject Master Experts
(SMEs)
• Formal Usability Inspections w/ user’s pre-screened
Assessing the Users’ Individual
Differences
• Cognitive/Theoretical Approach
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Test subjects pre-screened
Browser/Solver
Field dependent/Field independent
Cognitive or Learning Styles Inventory
• Less Theoretical Approach
– Roles in the Organization?
– Experienced vs. Novice
• 3 Fundamental dimensions along which users’
experience differs
• Subject Domain, System/Application, Computer Use
Server Logs for Looking at Overall
Web Page Usage
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Where did server call originate?
How long on a particular page/link?
Which internal links used? In what order?
Number of links used? Efficiency of path choice?
Metrics for search efficiency, effectiveness,
relevance?
• Task time/Number of nodes visited - most common
• Click stream data
Browser Tools Used as Indicators
of Usage
• “Linear” Tools: Back/Forward, Embedded
Links
• “Jump” Tools: Go, History list, Home, etc
• Bookmarks used as markers of relevant
content
• Email sent to others.
Looking at the User’s On Screen
Behavior and Attitudes
• Surveys, Online and Field-based, Focus Groups
• Function Key Coding (tied to time stamped video)
• Log Analysis
– Investigator www.winwhatwhere.com
• Video Tape
• Screen Navigation Capture
– Lotus’ ScreenCam www.lotus.com
– TechSmith’s Camtasia www.camtasia.com
Current Voices and Resources
• Jakob Nielsen, prolific
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w/ Robert Mack, Usability Inspection Methods, 1994
Usability Engineering, 1993
Designing Web Usability, 2000
useit.com
• Keith Instone, usableweb.com
• Jared Spool, Web Site Usability
• Garlock and Piontek, Designing Web Interfaces to
Library Services and Resources
• Lab Equipment www.userworks.com
A Suggested Immersibility Index
• Problem: People from different disciplines judge the success of
Web sites differently.
• Solution: Immersibility Index was created to measure a site
holistically.
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Functionality - site’s delivery of interactive service
Usability - ease of use of all site components
Branding - site’s projection of desired image and feel
Content - information that the site offers (includes all media)
• Each dimension provides statements with 5-point Likert scale.
• Radar chart is created using summative assessments.
What Understandings Exist about
Interface Design?
• Visibility of System Status (for each user action/some
reaction)
• Match Content to User’s Real World
– language, avoid jargon
– follow real-world conventions
– follow natural, logical order - “Return to” buttons
• User Control and Freedom
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clearly marked exits
undo and redo
make it hard to perform irreversible actions
assist user with error recovery
More Interface Understandings
• Consistency and Standards
– “two clicks to content”
• Recognition over Recall
– why visual clues surpass memorized commands
• Flexibility and Efficiency of Use
– Regular and Advanced Search
• Aesthetic and Minimalist Design
Understandings about Web Design
• Chunking, “7 plus or minus 2”
– assigning a semantic clue to aid recall
– cluster like information nearby
– white space around a cluster aids memory
• Inverted Pyramid Writing Style
– big picture first, details added farther along
– guidance from journalism
More Web Design Understandings
• Important information “above the fold”
• Avoid gratuitous use of features (e.g., animation,
frames, etc.)
• Make the site scannable
– sans serif fonts
– self-describing hyperlinks
– brief, easily digestible paragraphs
• Online help and documentation at least
Physiological Understandings
• Keep Download and Response Times Low
– 1/10 second for “instantaneous” sense
– 1 second for uninterrupted flow of thought
– 10 seconds for keeping user’s attention on dialogue
• Animation
– have overpowering effect on peripheral vision
• Color
– status change, color change - visited links
– High contrast attracts attention
– Minimize color variety - blue and green most soothing