Michael Gaigg: Über UI/UX Design


What is Usability?

Posted by Michael Gaigg

Before I dive into guidelines and tips of designing and implementing usable websites I feel it is important to define and outline what Usability is. Please allow me at this point to cite several sources that I find essential.

Usability is the

  • Effectiveness (accuracy and completeness to achieve goals)
  • Efficiency (resources expended in relation to the accuracy and completeness)
  • Satisfaction (comfort and acceptability of the work system to its users)

with which specified users achieve specific goals in particular environments. [ISO9241]

Basic Principles

Alan Dix formulates in his book 'Human-Computer Interaction' that above definition can be concluded into three basic principles:

  • Learnability (the ease with which new users can begin effective interaction and achieve maximal performance)
  • Flexibility (the multiplicity of ways the user and system exchange information)
  • Robustness (the level of support provided to the user in determining successful achievement and assessment of goals)

Five Quality Components

Jakob Nielsen uses human characteristics to extend these principles by saying:
Usability has 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?

with the addition of 'utility' (functionality): Does it do what the user needs?

Implications for Usability Design

Implications drawn out of above definitions are that pages shall strive (devote serious effort or energy) to provide:

  • Consistency of presentation and controls across the site
  • Logical and natural organization of information (clear structure, systematic, clear and meaningful labels)
  • Contextual navigation (how much information is given for providing a context for the user; where is he/she in the site? Where can he/she go? How can he/she go back?)
  • Efficient navigation (the amount of time and effort the user needs to exert in order to move around the site)
  • Adequacy of feedback (are user interactions clear, are requests answered, do commands elicit the right response?)
  • Searchability (how effectively the site content can be sought in search engines?)
Suggested reading:

Visual Web Design

Posted by Michael Gaigg

First impressions matter! Luke Wroblewski, an excellent speaker with original insights which I had the pleasure to hear at last year's UI-12 (User Interface 12) in Boston, states in his latest article that users coming to your site from a search engine will do one of three things:

  • Look over the page and determine it is not relevant to their goal
  • Look over the page and determine it might be relevant to their goals then quickly scan the page for the information they need
  • Look over the page, quickly scan the page, find the information they need and then stay awhile.

All this happens within seconds. Therefore it is necessary to translate the first impressions (what am I looking at? functional role present?) into meaningful interactions, i.e. scanability, further (inter)action, which leaves us with the following

Guidelines for Visual Web Design

  1. Set initial expectations by communicating what kind of information it provides.
  2. Provide a way to quickly scan that information in order to locate something of value.
  3. Allow people to immerse themselves in the information they want and explore other relevant information when they choose to.
Suggested reading: