What are the categories of usability goals?

Usability goals

Usability goals are the criteria for an interface to measure its ease of use. It's a crucial step of the interface design to set usability goals. It's essential to evaluate the interface by comparing it with some requirements. Usability goals provide the criteria for that. These goals are set before the design process starts and are then compared with the end product to see if the requirements have been met.

Categories of usability goals

Usability goals can be categorized into several broad or narrow types. The different types of usability goals include the following:

Qualitative goals

Qualitative goals are a broad category of usability goals. They're unquantified goals with generic requirements. Consider the following for example:

The design must support expert users working in a noisy environment, with contextual information on the screen to remind users about the task when they get distracted.

Quantitative goals

Quantitative goals are another broad category of usability goals. They're objective and have some measurable numeric value associated with them. Such goals help evaluate an interface design objectively because the quantity mentioned can be measured and compared. Consider the following for example:

First-time users should take no longer than four minutes to fill in the data form.

Ease-of-use goals

Ease-of-use goals focus on expert users with prior experience working with similar interfaces. Such goals aim to provide expert users with an interface that helps them perform the tasks efficiently. Speed of performance is an essential factor in ease-of-use goals. An example of an ease-of-use goal is as follows:

Experienced users should take no longer than one minute to fill in the data form.

Ease-of-learning goals

Ease-of-learning goals apply to novice users who either use the interface for the first time or use it so infrequently that they need to be guided every time. Such goals intend to measure the learning curve of first-time users. The quantitative goal mentioned above is an example of an ease-of-learning goal as well.

Absolute goals

Absolute goals refer to some specific quality, which is not measured comparatively to another. Therefore, such goals are independent and do not have to be measured against some other quantity. The examples given above are absolute goals as well.

Relative goals

Relative goals compare the user's experience with some benchmarks. The benchmark can be a competitor's product or a previous version of the interface under design. The interface is then evaluated relative to the benchmark. Consider the following for example:

Novice users should take less time on average filling the data form on version 2.0 compared to version 1.0.

Performance goals

Performance goals deal with the actual execution of the tasks by the users. The actions performed are evaluated by time and number of errors. The time can be for either completing the task or learning it. All the previously mentioned examples are performance goals as well because they evaluate the user's performance in terms of time.

Preference goals

Preference goals intend to develop a user's inclination towards the interface, among other alternatives. These are evaluated by measuring the average number of users who prefer the interface under design over others. Consider the following for example:

90% of users should choose the interface design of application X over application Y.

Satisfaction goals

Satisfaction goals aim to measure users' satisfaction levels with the interface under design. These goals are objective and usually measured by asking the users to rate their satisfaction with the interface. Consider the following for example:

Expert users must rate their satisfaction with the interface as a 4 on average, given a 5-point rating scale with 1 being 'Not satisfied' and 5 being 'Extremely satisfied.