Fundamentals of Usability

What is usability?

Usability is a quality attribute that assesses how easy user interfaces are to use. The word "usability" also refers to methods for improving ease-of-use during the design process.

Usability is defined by five quality components:

  • Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?
  • Efficiency: Once users have learned the design, how quickly can they perform tasks?
  • Memorability: When users return to the design after a period of not using it, how easily can they reestablish proficiency?
  • Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
  • Satisfaction: How pleasant is it to use the design?

Why usability is important

  • If your website is difficult to use, people will leave. If the interface and navigation are not clear, or the information is difficult to read, users will go elsewhere.
  • The easiest way to determine the usability of your site is by conducting user testing. User testing is not to be confused with focus groups. Typically, five users is sufficient.
  • View some common misconceptions about usability and user testing.

Simple Usability Text

  • Find five users who fit your primary target audience.
  • Ask the users to perform three specific tasks on your site. For example, a task may be to find the undergraduate application form or locate information on how to register for orientation.
  • Observe what they do, where they succeed, how long it takes and where they have difficulties with the interface and content. It is important you do not help them and let them problem-solve on their own. Encourage them to think out loud so you can take notes on their thought processes as they complete each task.


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