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What is the spectrum of Usability? What does it cover?

According to the ISO 9241-10 definition, Usability is:

Extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency, and statisfaction in a specified context of use.

U

sability does not only concentrate on beginners, but also takes the advanced users into account to improve the overall handling of the product for every user. Usability is about usage, task, performance, and task support. Every user should be able to reach his goals easily by using the product in a way that suits him (e.g. simple mouse clicks for beginners or keyboard shortcuts for power users).

What is the advantage of technology free wording in the design process?

By keeping the design process on an abstract level above the actual technology the results can be used to engineer a various range of actual platforms (e.g. a GUI or a display on a machine). Also the results have a longer lifetime because technology may change after a while.

What is the advantage of using a methodology for usability design?

Design is quite hard to teach because it is a creative process and you need a certain feel for it. A methodology helps designers to get theirs thoughts straight and reduce the abstract design process to a more practical process that can be understood and followed by other people.

Why do we structure in Actors, Roles, and Task Cases?

The main goal of the design process is to create a presentation and interaction design that fits the customer's needs best. To be able do that the designer needs as much information as he can get about the tasks a user of the product wants to perform. By structuring the user's interaction with the product in the above parts the designer gets a feeling for his users and what they want to do with the product. The structure gets more and more detailed from a simple definition of user groups to a detailed description of the interaction dialogs for the single tasks.

What is the main output of the task map and the navigation map?

On the task map the designer clusters all task cases that belong together to help the user in fulfilling his tasks. These clusters are then put on the navigation map to define a simple navigation between them. The result is the basic structure and organization of the product.

Why do we need an abstract prototype?

The abstract prototype closes the gap between data and action on the one hand and visual design on the other hand. In the abstract prototype the data and the actions are identified from the task cases and clustered together so that they can then be given a visual design in the visual prototype.