Usability
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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. Usability can also refer to the methods of measuring usability and the study of the principles behind an object's perceived efficiency or elegance.
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.
Introduction
The primary notion of usability is that an object designed with the users' psychology and physiology in mind are, for example:
- More efficient to use—it takes less time to accomplish a particular task
- Easier to learn—operation can be learned by observing the object
- More satisfying to use
In the user-centered design paradigm, the product is designed with its intended users in mind at all times. In the user-driven or participatory design paradigm, some of the users become actual or de facto members of the design team.
The term user friendly is often used as a synonym for usable, though it may also refer to accessibility. The use of terms user friendly and user friendliness should be avoided, as there are no widely accepted definitions for them, and they are thus often used without much substance.
There is no consensus about the relation of the terms ergonomics (or human factors) and usability. Some think usability as the software specialization of the larger topic of ergonomics. Others view these topics as tangential, with ergonomics focusing on physiological matters (i.e. turning a door handle) and usability focusing on psychological matters (i.e. recognising that this door can be opened by turning that handle).
Defining usability
Usability is often associated with the functionalities of the product (cf. ISO definition, below), in addition to being solely a characteristics of the user interface (cf. framework of system acceptability, also below, which separates usefulness into utility and usability). For example, an automobile lacking a reverse gear could be considered unusable according to the former view, and lacking in utility according to the latter view. However, it is to distinguish between Usability and Usability Engineering. Whereas traditional Usability is rather concentrating on testing existing software, Usability Engineering (UE) is including usability methods within the software development process.
ISO standard
the document ISO 9126 (1991) Software Engineering Product Quality issued by International Organization for Standardization defines usability as:
- A set of attributes that bear on the effort needed for use, and on the individual assessment of such use, by a stated or implied set of users.
- The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.
Jakob Nielsen's framework of system acceptability
Usability consultant Jakob Nielsen and computer science professor Ben Shneiderman have written (separately) about a framework of system acceptability, where usability is a part of usefulness and is composed of:
- Learnability (e.g. intuitive navigation)
- Efficiency of use
- Memorability
- Few and noncatastrophic errors
- Subjective satisfaction
Usability considerations
Usability includes considerations such as:
- Who are the users, what do they know, and what can they learn?
- What do users want or need to do?
- What is the general background of the users?
- What is the context in which the user is working?
- What has to be left to the machine? What to the user?
Other considerations include:
- Can users easily accomplish their intended tasks? For example, can users accomplish intended tasks at their intended speed?
- How much training do users need?
- What documentation or other supporting materials are available to help the user? Can users find the solutions they seek in these materials?
- What and how many errors do users make when interacting with the product?
- Can the user recover from errors? What do users have to do to recover from errors? Does the product help users recover from errors, for example, does software present comprehensible, informative, non-threatening error messages?
- Are there provisions for meeting the special needs of users with disabilities? (accessibility)
Usability is now recognized as an important software quality attribute, earning its place among more traditional attributes such as performance and robustness. Indeed various academic programs focus on usability. [link] Also several [usability consultancy companies] have emerged, and traditional consultancy and design firms are offering similar services.
See also
- Internationalization
- Social Interaction design
- Usability testing
- Web usability
- Interaction design pattern
- Universal Usability
References
- Jakob Nielsen: Usability Engineering, Morgan Kaufmann Publishers, ISBN 0125184069
- Ben Shneiderman: Software Psychology, 1980
- Andreas Holzinger: Usability Engineering for Software Developers, Communications of the ACM (ISSN: 0001-0782), Vol. 48, Issue 1 (January 2005), 71-74, 2005
External links
See also external links for Web usability.Professional Associations
- [Usability Professionals' Association] — an organization for people practicing and promoting usability
- [ACM SIGCHI] — the ACM's Special Interest Group on Computer-Human Interaction
- [STC Usability & User Experience Community] — Usability and User Experience Community of the Society for Technical Communication
- [Human Factors and Ergonomics Society (HFES)]
Research & Peer-Reviewed Journals
- [The Centre for HCI Design is London's largest HCI-related research group, City University, School of Informatics]
- [The Virtual Usability Lab]
Design Critiques
- [Bad Human Factors Designs] — examples of bad design
References
- [Interaction-Design.org] — an open-content encyclopedia about usability
Lists of Links
- [Human Factors International Suggested Links]
- [EServer TC Library: Usability]
- [Usability Views] — collectes links to articles and news related to usability
Fun
- User Friendly — User Friendly webcomics
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