Usability Engineering

The key success of a software project is not only technical. It is the purpose of Usability Engineering to integrate the user perspective to the development process.

Usability Engineering allows to reduce the development costs by simulating from the beginning of the project, the software use.

Methods

Usability Engineering is based on an iterative development process with several evaluation phases aiming at identifying problems and improving the product. We present here the major methods of user evaluation:

  • Ergonomic evaluation is carried out of the context of use of the software by an usability specialist.
  • On the opposite, user testing is led in a real context of use.

These methods allow to identify the usability problems and to improve usability. They can also be used for comparing the usability of different products.

Other methods are employed during the development in order to guarantee the adequacy with the user's needs. Particularly, the prototyping is used to consolidate the software or the website design.

Stakes of Usability Engineering

During software development, the usability engineering process allows to reduce costs. By integrating the end-user during the design phase, the development team can quickly consolidate their understanding of the users' needs.

Given that 70% to 80% of the costs are engaged at the beginning of the project, the stake is significant. A better understanding of the effective use of the software and of the users' demand allows to reduce the risks and to avoid unplanned returns and the related overcosts, due to a bad understanding of the real usage conditions.

Furthermore, J. Nielsen has shown that the man-machine interface was the subject of approximately a third of the progress meetings during software development. Actually, from the customer's point of view, the interface usability is a major criterion of choice of a product. By integrating the user in the design and the evaluation of the man-machine interface during prototyping phases, usability engineering contributes to risk reduction.

Usability Engineering impacts the total cost of the project in a more and more significant way since most applications are now interactive. The interface takes a significant place of the developed code: on average 48%, even 80% for the web applications.

Of course, Usability Engineering also has a cost. It is estimated to approximately 6% of the total cost of the project [Nielsen 93]. This investment is relatively low compared to the stakes which are the quality of the product and the customer satisfaction.