Evaluation 44

In order to improve usability, the most basic method is user testing. According to Nielsen, this method has three components (Nielsen, 2003b):

• Get hold of some representative users, such as customers for an e-commerce site or employees for an intranet (in the latter case, they should work outside your department);

• 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. Let the users do the talking.

To identify a design's most important usability problems, testing five users is typically enough. Rather than run a big, expensive study, it is a better use of resources to run many small tests and revise the design between each one so the usability flaws can be fixed as

they are identified. Iterative design is the best way to increase the quality of user experience. The more versions and interface ideas tested with users, the better (Nielsen, 2003b).

According to Nielsen, usability plays a role in each stage of the design process. He recommends the following main steps (Nielsen, 2003b):

• Before starting the new design, test the old design to identify the good parts that should be kept or emphasised, and the bad parts that give users trouble.

• Unless working on an intranet, test competitors' designs to get cheap data on a range of alternative interfaces that have similar features to one’s own.

• Conduct a field study to see how users behave in their natural habitat.

• Make paper prototypes of one or more new design ideas and test them. The less time invested in these design ideas the better, because they all will need to be changed based on the test results.

• 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.

• Inspect the design relative to established usability guidelines, whether from one’s own earlier studies or published research.

• Once the final design is decided upon and implemented, test it again. Subtle usability problems always creep in during implementation.

One should not defer user testing until there is a fully implemented design. If user testing is deferred, it will be impossible to fix the vast majority of the critical usability problems that the test uncovers. Many of these problems are likely to be structural, and fixing them would require major redesigning. 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 (Nielsen, 2003b).

After usability and accessibility principles and guidelines have been implemented, the user interface should be evaluated according to Nielsen (Nielsen, 1994). This user-

interface evaluation is called a heuristic evaluation. Heuristic evaluation is a usability engineering method for finding the usability problems in a user-interface design so that they can be attended to as part of an iterative design process. Heuristic evaluation involves having a small set of evaluators examine the interface and judge its compliance with recognised usability principles (Nielsen, 1994).

In general, heuristic evaluation is difficult for a single individual to do because one person will never be able to find all the usability problems in an interface. Luckily, experience from many different projects has shown that different people find different usability problems. Therefore, it is possible to improve the effectiveness of the method significantly by involving multiple evaluators (Nielsen, 1994). Nielsen suggests the heuristic evaluation is performed by having each individual evaluator inspect the interface alone. Only after all evaluations have been completed are the evaluators allowed to communicate and have their findings aggregated. This procedure is important in order to ensure independent and unbiased evaluations from each evaluator. The results of the evaluation can be recorded either as written reports from each evaluator or by having the evaluators verbalise their comments to an observer as they go through the interface. Written reports have the advantage of presenting a formal record of the evaluation, but require an additional effort by the evaluators and the need to be read and aggregated by an evaluation manager. Using an observer adds to the overhead of each evaluation session, but reduces the workload on the evaluators.

The output from using the heuristic-evaluation method is a list of usability problems in the interface with references to those usability principles that were violated by the design in each case, in the opinion of the evaluator. It is not sufficient for evaluators to simply say that they do not like something; they should explain why they do not like it with reference to the heuristics or to other usability results. The evaluators should try to be as specific as possible and should list each usability problem separately (Nielsen, 1994).

Heuristic evaluation does not provide a systematic way to generate fixes to the usability problems or a way to assess the probable quality of any redesigns. However, because

heuristic evaluation aims at explaining each observed usability problem with reference to established usability principles, it will often be fairly easy to generate a revised design according to the guidelines provided by the violated principle for good interactive systems. Also, many usability problems have fairly obvious fixes as soon as they have been identified (Nielsen, 1994).

3.6 Conclusion

The research into the accessibility and usability standards and guidelines as well as Web design standards showed the close and important relationships between these disciplines in designing a website.

Web design guidelines indicated the importance of having consistent Web element behaviours, functionality and look throughout a site as users become accustomed to the way a site behaves. They come to expect certain elements to work in a certain way. Deviations from this expected behaviour could lead to a user finding a site difficult to use (decreased usability) and ultimately leaving the site.

Following accessibility standards and guidelines means that people with disabilities can interact with and contribute to the Web. Accessible websites enable people with disabilities to use and contribute to the Web more effectively. By having an accessible site, more people with disabilities, various user agents and devices can use the site.

Usability refers to the ease of use of a website. A site should be usable, enable the users find answers to their questions and prevent the users from getting lost. The use of sites without accessibility and usability features implemented in them could lead to users leaving the site. This could mean the potential loss of customers on commercial sites, and users not being able to productively contribute on corporate websites. Post- implementation evaluations of standards and guidelines provide a way of identifying and addressing compliance issues.