Gathering usability feedback is an important step for creating user-friendly solutions. This applies to interactive systems (software, hardware, services) that are still in development as well as to solutions that are already released and that shall be further optimized. A project team itself can usually not judge usability because after a while, organizational blindness takes hold. – Solutions appear very “intuitive” to its creators after a while, because it is impossible to view them with the eyes of a user who has never seen them before. Therefore, it is highly recommendable to have a professional usability evaluation.
The Agony of Choice
When researching options for gathering usability feedback, one quickly discovers the approaches “usability inspection” and “usability test”. Both provide data regarding the usability of the system in question. Depending on the circumstances of a concrete project and the system to be evaluated, one or the other approach can be more expedient for getting usability feedback.
The usability test is an empirical approach that is characterized by the inclusion of representative users. In order to elicit usability information, users are asked to perform realistic tasks with the system in question. While doing so, they are observed to identify obstacles and problems that impair usability. The observation is supplemented by an interview to shed more light on critical issues.
The usability inspection does not require the inclusion of users. Instead, usability experts evaluate the user interface. To do so, they rely on their expertise as well as on established usability guidelines. While taking into account information on users of the system and their tasks, they peruse the user interface and identify instances where usability guidelines are not followed and where usability is potentially diminished.
Criteria for Choosing an Appropriate Approach
Both approaches can provide relevant information on system usability and therefore a basis for optimization. The choice of approach depends on several factors, four of which are now described.
Usability test and usability inspection usually differ in required effort and therefore in cost. Since a usability test relies on the inclusion of representative users, budget for planning and conducting the individual test sessions has to be factored in. In addition, costs for compensating participants can occur. The required budget for conducting a usability inspection is usually smaller since all costs that would be related to actual users do not apply.
Time Until Results Become Available
Requiring representative users usually also means that the time between planning the usability evaluation and the availability of results is longer for a usability test compared to a usability inspection. A usability inspection can be conducted relatively “spontaneously” since the dependencies mentioned do not exist. Therefore, results become available relatively soon after “project kickoff”.
The arguments mentioned so far seem to make a usability inspection the superior choice compared to a usability test. But there are additional aspects to keep in mind which can render a usability test the better choice.
Specifity of User Group
Some interactive systems more or less address the general public as user group, e.g. web shops. Other systems are characterized by a very specific user group conducting very specialized tasks, e.g. systems that are operated by medical personnel after years of training. Usability experts that conduct a usability inspection take into account information on users and their tasks. They are, however, not representative users themselves. This can make it difficult or impossible to fully take the perspective of users into account, which can result in certain relevant usability problems going unnoticed, especially those related to relevant (sub)tasks that are not familiar to the usability experts.
Depth and Breadth of Desired Results
A usability inspection can be well-suited when the goal is eliciting initial information regarding system usability, e.g. regarding established general usability standards and guidelines for user interface design. If the goal, however, consists in evaluating a system as comprehensively as possible and thoroughly taking the user perspective into account, a usability test can provide a clearer and more detailed picture. This is because the setting of a usability test – representative users working on realistic tasks – matches the real-world situation more closely than usability experts inspecting the user interface. The users contribute their extensive experience as well as their – per definition – highly relevant personal perspective.
Usability inspection as well as usability test aim at providing information regarding system usability.
If it is paramount to get results as quickly and cost-effectively as possible, a usability inspection is often a good option.
If the system in question has a very specific user group conducting very specialized tasks and if the evaluation shall provide results of significant breadth and depth, a usability test can be the more appropriate choice.
In practice, it often is not necessary to choose one approach over the other. The two can also be combined by initially conducting a usability inspection to realize usability optimization “quick wins”. Later in the project, after the system has been optimized accordingly, a usability test can be conducted in order to uncover more specific usability problems that went unnoticed during the usability inspection. By implementing such a combination of approaches, resources for the usability evaluation of a system can be used very efficiently.