What is usability?

What exactly is usability and how can the foundation for an intuitive user interface be laid? In this article I will use the definition of the ISO 9241-11 and explain it in detail.

The definition describes usability as follows:

"Usability describes the extent to which a product can be used by a certain user in a certain context to fulfill certain goals efficiently, effectively and goal-oriented."

Thus it becomes clear that the user is in the center of the considerations and the product to be developed should support him in a certain context of use to reach his goal. In order to get to know the user, usually the investigations of the marketing department are consulted, studies are read or struggled through sinus milieu definitions. By this approach, people are assigned to a certain group based on demographic data.  But is this the information that is crucial for the development of a new user interface? I say no. Because other factors are decisive here, such as experience with the task, experience and attitudes towards the technology itself and, last but not least, one's own skills.

Besides the user, the context is also crucial. The usage context describes the general conditions the interactive product has to face. In addition to the user, these are the tasks, working tools and the technical social environment. These conditions must be known in order to make the right decisions for the product. How do we get the useful insights from our users to get a comprehensive picture? Well, actually quite simply, we ask them. This can be done through semi-structured interviews using pre-defined guiding questions. To ensure that no information is lost, this information is written down and evaluated in essays in understandable language (in so-called context scenarios).

It should not be forgotten that the product always pursues a specific goal. Good usability means that a goal has been achieved effectively, efficiently and satisfactorily. Effectiveness describes the first level, the fact that the user can achieve his goal by using the product. One should take a closer look at the principles of efficiency, because this is about optimizing the effort required to achieve the goal.

Aufgabenangemessenheit, Selbstbeschreibungsfähigkeit, Steuerbarkeit, Erwartungskonfirmität, Fehlertoleranz, Individualisierbarkeit, Lernförderlichkeit
Graphic Dialog Principles

If the 7 dialogue principles of efficiency are fulfilled in the development of the product, the third criterion - satisfaction - is almost in the bag. Satisfaction describes the positive attitude of the user towards the product.

How to proceed best to design a usable product will be the topic of one of my next articles.

Anja Stork

UX Consultant


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