WEB USABILITY EXPLAINED

(For THE Complete Web Usability Site - See Jakob Nielsen's: Use It)

The most basic and useful is method for studying usability is user testing, which has three components:

• Getting representative users.
• Ask the users to perform representative tasks with the design.
• Observe what the users do, where they succeed, and where they have difficulties with the user interface. Shut up and let the users do the talking.

Usability has five components:

• Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?
• Efficiency: Once users have learned the design, how quickly can they perform tasks?
• Memorability: When users return to the design after a period of not using it, how easily can they reestablish proficiency?
• Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
• Satisfaction: How pleasant is it to use the design?

A key attribute is utility, which refers to the design's functionality: Does it do what users need? Usability and utility are equally important: It matters little that something is easy if it's not what you want. On the Web, usability is a necessary condition for survival.

• If a website is difficult to use, people leave.
• If the homepage fails to clearly state what a company offers and what users can do on the site, people leave.
• If users get lost on a website, they leave.
• If a website's information is hard to read or doesn't answer users' key questions, they leave.

There are plenty of other websites available; leaving is the first line of defense when users encounter a difficulty.

Usability plays a role in each stage of the design process.

1. Before starting the new design, test the old design to identify the good parts that you should keep or emphasize, and the bad parts that give users trouble.
2. Test competitors' designs to get cheap data on a range of alternative interfaces that have similar features to your own.
3. Conduct a field study to see how users behave in their natural habitat.
4. Make paper prototypes of one or more new design ideas and test them. The less time you invest in these design ideas the better, because you'll need to change them all based on the test results.
5. Refine the design ideas that test best through multiple iterations, gradually moving from low-fidelity prototyping to high-fidelity representations that run on the computer. Test each iteration.
6. Inspect the design relative to established usability guidelines, whether from our own earlier studies or published research.
7. Once we decide on and implement the final design, test it again. Subtle usability problems always creep in during implementation.

The only way to a high-quality user experience is to start user testing early in the design process and to keep testing every step of the way.