Towards a proposal to capture usability requirements through guidelines

Usability is a quality attribute related to effectiveness, efficiency and satisfaction of the end-users when they interact with a system. There are sound usability design guidelines that aim to optimize the system usability. However, it is difficult to work with them if there is not a previous background in the Human-Computer Interaction area. Moreover, in the Software Engineering community, there are not specific methods to capture usability requirements. Usually, usability requirements are gathered with other non-functional requirements such as security or reliability, even though the goals of these non-functional requirements are not the same as the goals of usability. This problem arises when we aim to include the usability requirements capture in a Model Driven Development (MDD) process, where an effective capture technique with an unambiguous notation is needed to represent these requirements. In this paper, we propose a new method to capture usability requirements at the early stages of the software development process in such a way that non-experts in usability can use it. In a first step, experts in usability organize several interface design guidelines and usability guidelines in a tree structure. Next, these guidelines are shown to the analyst (non-expert in usability) through questions that she/he must ask the end-users. Answers to these questions mark the path through the tree structure. At the end of the process, if we gather all the end-user's answers, we have the usability requirements. These usability requirements could be transformed into a conceptual model of any existing MDD method by means of model to model transformations.