Heuristic evaluation and user testing
There are two popular methods that can be used to found usability problem. Heuristic evaluation which is involving usability and interface design expertise to do website evaluation in order to find usability problem. Heuristic evaluation was founded by Nielsen15 years ago, and applying ten heuristic rules as an evaluation guideline. The second method is user testing where website users are tested to complete particular task and draw the problem occurs.
Purposes:
Both of them has purpose to find usability problem but with different emphasis. Heuristic evaluation mostly found minor usability problems, and even though the heuristic also found some major problems but the number of minor problem still outweigh the major problem. However, in user testing, user hardly found minor usability problem, but they really aware of major usability problem.
The number of people involves:
There is no strict number of evaluator who will involve during the evaluation. It is good to have more than one expert to do evaluation. The reason is the number of problem founding will increase when the number of evaluator increase (Kantner & Rosenbaum, 1997). For example with three evaluators may found more that 60% of the usability problem and 15 evaluators will found almost 90% of usability problems. But the ideal number of evaluator is 2-3 evaluators; in fact, some companies only need one evaluator to evaluate usability. In usability testing that involves user, increase the number of respondent in order to gain the same problem it’s not necessary. With 5 respondents will found up to 85% usability problems.
Advantages and disadvantages
Heuristic evaluation is the easiest method to found usability problem, it’s efficient where each evaluator may spent four hours to evaluate a website, and less expensive and faster. The disadvantage is sometimes we found ‘false positives’ or we found problem that not a problem. Usability testing could be more effective to found the real problem, very user centrist that focus on users need. In some area, user testing is more accurate because it use the real user and real task, and the problem finding is more real, compare to heuristic test that may find some false positive. However, user testing is more time and money consuming, from develop the task, choosing the right user, conduct the user testing, and interpret the result.
Conclusion:
Usability problem can be found either using heuristic evaluation or usability testing. Both of the methods have advantages and drawbacks. In fact those two methods can be used together to gain better result to identify usability problem. Heuristic evaluation offers easy way and quick finding of usability problem, but user testing can give more accurate information about the usability problem may occurs from real task and real user perspective. It is clear that matching of reality (user perspective) and standard convention (heuristic evaluation/expertise overview) is the best way to increase usability and overcome the problem.
 References:
Bailey, B. (2001). Heuristic evaluations vs. usability testing part 1Â Â Â Â Â Â Â Â Â Â Â Â http://www.webusability.com/article_heuristic_evaluation_part1_2_2001.htm
Kantner, L. & Rosenbaum, S. (1997). Usability studies of WWW sites: heuristic evaluation vs. laboratory testing. http://www.teced.com/PDFs/sigdoc97.pdf
Nielsen, J. (200u). Characteristics of usability problems found by heuristic evaluation. http://www.useit.com/papers/heuristic/usability_problems.html
Nielsen, J. & Mack, RL. (1994). Usability inspection methods. John Willey & Sons, Inc.
Straub, K. (2003) Pitting usability testing against heuristic. http://www.humanfactors.com/downloads/sep03.asp#kath.  UI Design Newsletter
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