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06/11/2010 / craigmartinallen

Computer Usability

Usability is seen as part of the overall system acceptability and has five components: 

  • Learnability
  • Efficiency
  • Memorability
  • Error handling
  • User satisfaction

Usability has to take into account not only the system itself but also the user’s experience, domain knowledge, and work environment. Usability heuristic principles include feedback, shortcuts, good error messages, and most important of all: consistency. Heuristic evaluation is described as one method of assessing usability in a cost-effective way.

Individual Users

Users define ‘usability’ as their perception of how consistent, efficient, productive, organized, easy to use, intuitive, and straightforward it is to accomplish tasks within a system. It is important for designers to develop an understanding of their users’ expectations through task analyses and other research. One of the basic principles of user- centered design is the early and continual focus on users. For this reason, user involvement has become a widely accepted principle in the development of usable systems. Involving users has the most value when trying to improve the completeness and accuracy of user requirements. It is also useful in helping to avoid unused or little-used system features. User involvement may improve the level of user acceptance, although the research is not yet clear that it does in all cases. Setting user performance and/or preference goals helps developers build better usability. It can also help make usability testing more effective. For example, some intranet Web sites have set the goal that information will be found eighty percent of the time and in less than one minute.

Do not have individuals make design decisions by themselves or rely on the ideas of a single designer. Most designers tend to adopt a strategy that focuses on initial, satisfactory, but less than optimal, solutions. Group discussions of design issues (brainstorming) do not lead to the best solutions. The best approach is parallel design, where designers independently evaluate the design issues and propose solutions. Attempt to ‘saturate the design space’ before selecting the ideal solution. The more varied and independent the ideas that are considered, the better the final product will be.

Personas are hypothetical ’stand-ins’ for actual users that drive the decision making for interfaces. They are not real people, but they represent real people. They are not ’made up,’ but are discovered as a by- product of an investigative process with rigor and precision. Interfaces should be constructed to satisfy the needs and goals of personas. Some usability specialists feel that designers will have far more success designing an interface that meets the goals of one specific person, instead of trying to design for the various needs of many. The design team should develop a believable persona so that everybody will accept the person. It is usually best to detail two or three technical skills to give an idea of computer competency, and to include one or two fictional details about the persona’s life.

Optimizing the User Experience

Designers should make every attempt to reduce the user’s workload by taking advantage of the computer’s capabilities. Users will make the best use of information when it is displayed in a directly usable format and content organization is highly intuitive. Users also benefit from task sequences that are consistent with how they typically do their work, that do not require them to remember information for more than a few seconds, that have terminology that is readily understandable, and that do not overload them with information. Users should not be required to wait for more than a few seconds for new information to appear, and while waiting, users should be supplied with appropriate feedback.

Let the computer perform as many tasks as possible, so that users can concentrate on performing tasks that actually require human processing and input. Ensure that the activities performed by the human and the computer take full advantage of the strengths of each.

(Notes taken from http://www.usability.gov/guidelines/)

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