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No.2 Usability Guidelines (April 4, 2001)
In order to improve the usability of a website, it is important to first establish the elements, or guidelines, that make a site usable. The site should then be designed according to those guidelines.
Jakob Nielsen, an authority on usability, summarizes the characteristics of usability in these five elements:
[Five Elements of Usability]
- Learnability :
Users can quickly adapt to the site and use it with ease.
- Efficiency :
Users can be highly productive once they have learned the design.
- Memorability :
Users can easily remember how to use the site.
- Few and Noncatastrophic Errors :
Users rarely make mistakes and recovery from errors is easy.
- Subjective Satisfaction :
Users find visiting the site enjoyable and satisfying.
 Learnability
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Learnability is a measure of how fast users can accomplish tasks the first time they visit a website. Websites with high learnability are generally said to have high usability. However, depending on the objective of the website heavy users may be the targeted audience. In such cases, efficiency during use is emphasized, and learnability can sometimes be sacrificed. Meanwhile, when designing websites for document requests or other sites that users may only visit once, learnability becomes the most important element in terms of usability.
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Efficiency
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Efficiency indicates how fast experienced users can accomplish certain tasks once they have learned the design. Online securities brokers and other sites that target heavy users must be designed with the efficiency of such savvy users in mind.
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Memorability
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Memorability is a measure of how quickly and accurately users can remember how to use a site that they have visited before. E-commerce and other sites that don't target users who visit often (like heavy users), but rather target users who only visit the site occasionally, must incorporate a design that enables users to quickly recall what they have learned and easily make purchases the next time they visit the site. Memorability and learnability are closely linked-the higher a site's learnability, the higher the memorability.
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Errors
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Fewer errors indicate that it is difficult for users to cause errors, and that even if errors occur, they are easily recovered. It is crucial to minimize errors, not only on a website, but also in a system. Confusing button layouts and error messages should be reevaluated making it difficult for users to make a mistake, and if an error does occur, the site design should allow the user to recover from the error without assistance, as much as possible.
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Satisfaction
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| Satisfaction is a measure of the degree of enjoyment users experience when visiting a site. This usability characteristic is especially important for entertainment-related sites such as Internet games and dating sites. Since users who visit these types want to spend time there and enjoy them, satisfaction in terms of entertainment value is a higher priority than the speed at which a user can accomplish a task. To keep users coming back to this type of site, designers must increase satisfaction levels so that sites are enjoyable and offer an active and rich experience. |
Website usability is not achieved through just one of these characteristics, but rather includes various ingredients made up of these five elements. The elements emphasized in a site will depend on its objective, but fundamentally, these five elements should be fulfilled to put usability into practice.
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