Usability

Draft

This article should be merged or at least coordinated with web usability - Daniel K. Schneider 18:31, 1 February 2011 (CET)

Definition

Usability is a term used to denote the ease with which people can employ a particular tool or other human-made object in order to achieve a particular goal. [...] In human-computer interaction and computer science, usability usually refers to the elegance and clarity with which the user interface of a computer program or a web site is designed. The term is also used often in the context of products like consumer electronics, or in the areas of communication, and knowledge transfer objects (such as a cookbook, a document or online help). It can also refer to the efficient design of a mechanical objects such as a door handle or a hammer. (Wikipedia: Usability - retrieved 17:30, 9 June 2006)

Usability can also refer to the methods of measuring usability and the study of the principles behind an object's perceived efficiency or elegance. (Wikipedia: Usability - retrieved 17:30, 9 June 2006 )

In more practical terms. ISO links usability to effectiveness, efficiency, and satisfaction, for a given product in a given context. According to the on-line Technical Layout & Design course (Technical Expressions, Inc,)

Usability specialists have expanded the ISO definition of usability, stating that a usable product is:

• easy to learn
• efficient to use
• provides quick recovery from errors
• easy to remember
• enjoyable to use
• visually pleasing

, retrieved 17:13, 26 January 2011 (CET).

See also:

• Cognitive ergonomics, Ergonomics (types of), HCI (human computer interaction)
• web usability, a sub-field of usability
• web accessibility, a sub-field of web usability that addresses the question of how to make websites usable by all sorts of people.
• User interaction and user interface design‎‎

Design methods

• See Usability Methods at usability.gov for the moment

Usability measures

The ISO dimensions of efficiency, effectiveness and satisfaction can be operationalized in various ways: Sauro and Kindlund, (2005), in their SUM index use a mean of four (standardized) measures:

• efficiency is measured through task times
• effectiveness is measured both through number of errors and task completion
• satisfaction is measured with a short questionnaire based on Lewis (1991).

In other words, the SUM index can be summarized as:

usability = 0.25 * z-score (task time)
          + 0.25 * z-score-equivalent (N erros)
          + 0.25 * z-score-equivalent (task completion)
          + 0.25 * z-score (satisfaction)

Links

Resources

(larger usability sites, alphabetically sorted)

• http://www.measuringusability.com/
• http://www.sensible.com/
• http://www.usabilityhome.com/
• http://www.usabilityinstitute.com/
• http://www.useit.com/
• http://www.usability.gov/
• http://www.usabilityfirst.com/

General introductions

See also web usability and user interaction and user interface design

The US Research-Based Web Design & Usability Guidelines

“Throughout your Web design or redesign project, you should take advantage of what is already known about best practices for each step of the process. The Research-Based Web Design and Usability Guidelines, compiled through an extensive process of research and review, bring you those best practices.”

• Full book
• Index of individual chapters

Various interesting pieces

• Jeff Sauro has a series of interesting blog pieces, e.g.:
  • 97 Things to Know about Usability, by Jeff Sauro | September 7, 2010. (A nice list that includes links for further reading).
  • 5 Second Usability Tests by Jeff Sauro, November 9, 2010.
  • The Five Most Influential Papers in Usability
  • 25 Resources for Measuring Usability Dec 2010.

• Usability 101: Introduction to Usability by Jakob Nielsen, retrieved 16:51, 18 November 2010 (CET)

• Guerrilla HCI: Using Discount Usability Engineering to Penetrate the Intimidation Barrier by by Jakob Nielsen, 1994.

• User-Centered Design: The Fable of the User-Centered Designer, A nice story in PDF or ePub format by David Travis. (free)

• Professional and Technical Writing/Design/Usability and Professional and Technical Writing/Instructions (chapters from the Wikibook on professional and technical writing)

• User in Your Face, The Student Programmer's Before-and-After Guide to Usability and Usable Interface Design, by Jack Bellis.

On Wikipedia

You may start from the Desing portal, a page that indexes most pages related to design including usability.

Sample pages:

• Usability
• Usability engineering
• Usability testing

Methods

• Both Usability and Usability engineering articles on Wikipedia include lists of methods (and pointers for further reading).
• The Usability Methods toolbox by James Hom
• Usability Evaluation
• Articles & Resources at UserFocus.co.uk
• sensible.com (Steve Krug)

On-line tools

• Usability Scorecard

Government

• Usability.gov (USA)

Standards

• ISO/TR 16982:2002 - "Ergonomics of human-system interaction—Usability methods supporting human-centered design"
• ISO 9241 - "Ergonomics of Human System Interaction" -
  • ISO 9241 Wikipedia summary

Bibliography

• Lewis, J. R. (1991). Psychometric evaluation of an afterscenario questionnaire for computer usability studies: The ASQ. SIGCHI Bulletin, 23, 78-81.

• Sauro, Jeff and Erika Kindlund, (2005). A Method to Standardize Usability Metrics into a Single Score, CHI 2005, PDF reprint