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13.5. The focus of the usability assessment

Depending on the state of the process reached, and the goals of the evaluation, usability assessment may focus on different aspects of quality of use. Here are some scenarios most commonly encountered in usability assessment:

Informational content of the application
The usability assessment of the informational content is performed to evaluate the correctness of the information provided by the system as well as the adequateness of the media selected for the presentation of information by the system. Evaluation at this level focuses on ‘deep’ aspects of the design of the application; it refers to the appropriateness of the system’s functionalities and information to support the user’s task.

Functionality of the user interface
This looks at features and properties of the dialogue and presentation components between the user and the user-interface of the application. The purpose of such features is to give the user access to the functions of the software provided for browsing and navigating through the information content, for searching, selecting, retrieving and storing of information and other more application-specific functions.

User performance
This looks at the ability of the end user to carry out the tasks for which the system is designed, in the context in which the system will be used. We may distinguish between two aspects of user performance: does the user get the correct information or generate the right outputs (effectiveness); and how long it takes the user achieve this output (efficiency).

Load imposed on the end user
This looks at the properties of the task, which the user intends to perform. This may be the result of properties of the information content or the functionality of the application, or the nature of decisions the user performs on the basis of this information. Stress in terms of cognitive load and subjectively experienced discomfort is a function of the load on the individual user, and factors such as individual differences, learning state, and fatigue.

Satisfaction of the end user
A software system may be highly efficient, and lead to effective outputs. However, the way the user reacts to the system is equally important. Subjective reactions include efficiency (does the user feel that they are working well with the system), perceived helpfulness, degree of control experienced by the user, the learnability of the software, and a general emotional reaction to the software system. These are all determinants of whether the system will be accepted in use, or if deployment of the system will be mandatory, the extent to which end user staff will experience job satisfaction.

Cost/benefit analysis
This kind of assessment focuses on what has to be done to the system in order that it should achieve a certain level of quality of use, and then considers the probable cost of carrying out the work needed balanced against the degree of criticality of the work. Alternatively it may consider the probable cost of the validation activities balanced against the criticality of the information to be obtained from such a procedure.
 
 
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Arunkumar Khannur, Software Testing - Techniques and Applications, Published by Pearson Publications, 2011 (ISBN:978-81-317-5836-6; Pages:341 + xxii)
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