Michael Gaigg: Über UI/UX Design

10Oct0

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:
7Oct0

What is Accessibility?

Posted by Michael Gaigg

The purpose of web pages is to interactively display information. The Hypertext Markup Language was designed to encode meaning rather than appearance. Therefore

Accessibility is the extent of access to information on a webpage through user agents (e.g. browsers, screen readers,…) which translate HTML into hypertext structures (links, headers, tables, forms,…) in order to give the users a surplus value.

“As long as a page is coded for meaning, it is possible for alternative browsers to present that meaning in ways that are optimized for the abilities of individual users and thus facilitate the use of the Web by disabled users. Those disabilities are:

  • Visual Disabilities
  • Auditory Disabilities
  • Motor Disabilities
  • Cognitive Disabilities” [NIELSEN96]

Since Web pages are highly visual and interactive the most affected groups as far as accessibility is concerned are the visual disabled, i.e. blind users or users with other visual disabilities like color blindness and users with motor disabilities using alternative input devices or sometimes even just the keyboard instead of the mouse.

Everybody benefits!

In the same way a sidewalk curb is necessary for wheelchair accessibility it also benefits parents with strollers, children with rollerblades and elderly persons trying to cross the street. The same is true for web pages. Designing for accessiblity will not only benefit users with disabilities but will also increase your:

  • Market Share Benefits
    • SEO (search engine optimization)
    • Repurpose
    • Literacy
    • Bandwidth
  • Technical Efficiency Benefits
    • Maintenance
    • Server Bandwidth