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Usability |
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Usability is not a single term, but a combination of many principles that apply to a software application. It questions whether that application is usable by common users. Whether users understand it ?. A few definition are:
- Learnability
- Ease of Use
- Error - Free Use
- Speed of Use
- Retention over Time
- Subjective Satisfaction
Usability Principles
- Conceptual Design
- Use Metaphores
- Use Constrains
- Affordances and Mappings
- Make controls look and feel different
- Affordances and mappings
- Direct Manipulation
- Consistency
- Feedback
- Visibility
- Standards
- Minimize User Memory and Task Load
- Modality
- Multiple Input Paths
- Customization
Usability Techniques
There are a variety of approaches to usability evaluation that you may choose to take. The methodologies can be divided into two broad categories: those that gather data from actual users and those that can be applied without actual users present. Of course the approach you choose to take must factor in variables such as the cost of evaluation, the appropriateness of the technique to your project, time constraints of the project, and the cost associated with the implementation and training of new users.
Usability evaluations can be conducted at many stages during and after the design and development process. In choosing a usability evaluation method, cost is invariably a consideration. But it is important to keep in mind that the value of a usability evaluation needs to be calculated not only in time and materials involved, but also in terms of the impact on the end-users, especially considering the cost of losing return visitors to your website due to unusable design.
- Cognitive Walkthrough is an approach to evaluating an interface based on breaking down and analyzing actions that a user must perform in order to use the system or perform a task.
- Focus Groups gather groups of users to get their feedback, initial reactions to a design, and discuss their preferences. Focus groups can be useful for raising issues that may not come out during interviews.
- GOMS is a family of techniques for modeling and describing human task performance. GOMS is an acronym that stands for Goals, Operators, Methods, and Selection Rules.
- Prototyping involves developing representations of a system for testing purposes and can range from simple sketches to almost fully functional systems.
- Task Analysis evaluates how the end-user actually uses software or websites. An analyst determines the user goals and tasks, then makes recommendations aimed at increasing efficiency and user-friendliness.
- Usability Inspection reviews a system based on a set of usability guidelines. Experts familiar with issues of usability in design perform the usability inspection.
- User Testing observes actual users interacting with software or websites. Users are asked to perform tasks while usability experts observe and take note of their actions.
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