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According to the "Usability Guide", which is a section of the ISO 9241 standard defined by the Turkish Standards Institute, usability is defined as the degree of usage pleasure / satisfaction for the effective, efficient usage, within a functionality framework, of a product by certain users, for certain aims. The effective usage of a product is evaluated by the user’s proper use for certain aims and reaching the wholeness, the product being used efficiently, however, is evaluated by the measure of resources spent in reaching proper usage and wholeness. In accordance to this standard the definitions of gratification, user, mission, aim, usability test, which are the main components of usability studies, are defined as below:

Satisfaction: Being away from usage hardships and the positive attitude using the product.

User: The person who interacts with the interface.

Tasks: The actions necessary to reach the aim.

Aim / The Aimed Output: The action which the user wants to accomplish.

Usability Test: The test is asking the user, who is a representative of the aimed mass to be going to use the interface, to perform the aimed tasks, and collecting the efficiency, effectiveness and satisfaction values during the process. After deciding on the aimed mass, that is, the users, the interface is put into use by asking them to perform the tasks commonly used on the interface or other important tasks to be reached for although they may not be used frequently.

The Usability Study

The evaluation of usability is conducted by getting the levels of affectivity, efficiency, and satisfaction from the user during the process of having the defined task completed by the target group for a certain interface.

Once the target group, the users, is set, they are asked to access the functions mostly used and/or rarely used but containing important information on the interface to be tested and thus the interface is put to use.

 The Steps Taken in the Usability Study

After the topic for the usability study is decided upon,

- The interface to be tested and other means (e.g. surveys) to be used are set.
- The Target user group is determined.
- The tasks for the target users are chosen.

After these four main components are designated the test stage is proceeded to. If there is a questionnaire among the other means of target to measure the user's attitude or knowledge before using the interface, it is given to the subject to fill in prior to the test. Then the tasks are given to the user one by one. For every task, information like success or no success, number of errors and duration are kept. During any task it is required of the user to think out loud so that where the user faced problems with the interface and what the user thinks about it is recorded. Throughout the test all the sayings and the actions of the subject is recorded by the observer. At the end of the test the user is given an impression query to yield the level of satisfaction with the interface.

In addition eye trackers may be incorporated during the processes of usability, however, to obtain concrete statistical information about the tendencies of the user while using the interface and its design.