Usability

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Usability Design I

• 13th February

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Effective Web Design

• Introduction to usability issues
• Evaluation and analysis of web-sites

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What is Usability?

• Usability is NOT
• Just common sense
• all art (and no science)
• stumbled onto by accident
• tacked on at the end
• free

• Usability IS
• intuitive, safe, error-free, enjoyable
• best designed in from the beginning
• best achieved by knowing your users
• The best predictor of customer satisfaction
• The next competitive frontier

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What is Usability?

• Usability can be defined as
• the capacity to be used by humans easily and
  effectively where,
• easily to a specified level of subjective
  assessment
• effectively to a specified level of human
  performance (Shackel, 1990)
• Usability affords the user easy access to the
  products functions

Usability Issues
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Users
User Groups
Age
Computer skills knowledge
Disabilities
Cultural
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Nielsens Heuristics

• Nielsen defined 10 usability principles that can
  be applied to any system, although frequently
  used for web applications
• Similar in aim to usability goals, except
  slightly more prescriptive
• Used mainly as the basis for evaluating systems
  
• Provide a framework for usability evaluation

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Nielsens Heuristics
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Nielsens Heuristics

• Visibility of system status
• Always keep users informed about what is going
  on, -gt provide appropriate timely feedback within
  reasonable time

• e.g. when screen button clicked on provides sound
  or red highlight feedback

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Nielsens Heuristics

• Match between system and the real world
• Speak the users language
• Dont use system oriented terms
• Use real world conventions to make information
  appear in a natural and logical order? Use a
  technique called mapping Relationship between
  controls and their movements and the results in
  the world

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Nielsens Heuristics

• Why is this a poor mapping of control buttons?

• Why is this a better mapping

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Nielsens Heuristics

• User control and freedom
• Provide ways of allowing users to easily escape
  and navigate to/from places they unexpectedly
  find themselves e.g.
• page forward / backward
• hold
• cancel
• end / stop
• help
• resume
• undo

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Nielsens Heuristics

• Consistency and standards
• Avoid making users wonder whether different
  words, situations or actions means the same thing
• Design interfaces to have similar operations and
  use similar elements for similar tasks
• Main benefit is consistent interfaces are easier
  to learn, use and remember

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Nielsens Heuristics

• Follow platform conventions
• Avoid confusion over whether different words,
  situations, or actions mean the same thing to
  user
• No custom link colours. They may conflict with
  rest of Web and make site hard to use.
• Web "standards"
• Follow HTML specifications
• Deviations from the standards results in
  unusable features creeping in

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Nielsens Heuristics

• 5. Help users recognise, diagnose and recover
  from errors
• Use plain language to describe the nature of the
  problem and suggest a way of solving it
• Careful design is better than good error messages
• prevents problems from occurring in the first
  place

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Nielsens Heuristics

• 6. Recognition rather than recall
• Make objects, actions, and options visible.
• Dont force user to recall information
• Instructions should be visible or retrieved
  easily when needed.
• From point of view of the Web, this heuristic is
  closely related to system status
• Users wont get lost if they can see where they
  are by looking at clues given by on current page.
• No need to recall their path to the home page.
• Good labels descriptive links are essential for
  recognition.
• Use images for links, but they need to be well
  designed.

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Nielsens Heuristics

• Error prevention
• Prevent them occurring in first place if
  possible
• Key question Does the system prevent users from
  making serious errors, and if they do make an
  error, does it permit them to recover easily

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Nielsens Heuristics

• 8. Flexibility and efficiency of use
• Provide accelerators that are invisible to
  novice users, but allow more experienced users to
  carry out tasks more quickly
• Use accelerators (keyboard shortcuts)
• Web Browser provides good accelerators e.g.
  bookmarks
• Design for effective book-marking
• contents of site can easily be linked to
• users create specialized views of a site for
  specific tasks

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Nielsens Heuristics

• 9. Aesthetic and minimalist design
• Avoid using info that is irrelevant or rarely
  needed
• No irrelevant or rarely needed information in
  dialogues -gt diminishes visibility
• Extraneous information on a page distracts user
  slows them down.
• Use progressive levels of detail.
• Support different uses of content. No brochures.

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Nielsens Heuristics

• 10. Help and documentation
• Provide information that can be easily searched
  and provides help in a set of concrete steps that
  can easily be followed
• Better if the system can be used without
  documentation
• it may be necessary to provide help and
  documentation
• Make it easy to search, focused on the user's
  task,
• list concrete steps to be carried out, and not
  too large.

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Pros and Cons Heuristic Evaluation

• Advantages
• detects both major (42) and minor (32) problems
  in UI
• more effective than single specialist
• can be used on designs
• realistic approach
• severity rating helps to set priorities

• Disadvantages
• groups can develop their own bias
• doing it properly is not that cheap
• new technologies (Web, Multimedia, Virtual
  Reality) may have specific problems not covered
  by The Heuristics

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Analyse this using Nielsens Heuristics
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Analyse this using Nielsens Heuristics
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Analyse this using Nielsens Heuristics
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Analyse this using Nielsens Heuristics
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Analyse this using Nielsens Heuristics
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References

• Shneiderman, B. Plaisant, C. (2005) Designing
  the User Interface
• Preece, J. et al. (2002) Interaction Design
• Benyon, D. et al (2005) Designing Interactive
  Systems

References