Usability Requirements

Within the iterative process, in this post is discussed the step "Specify the user requirements". The user requirements analysis, is the stage where failure occurs most commonly, get right requirements is crucial. Unfortunately, usability requirements are rarely identified by organizations purchasing or developing software. The purpose of this step is to establish usability requirements which can be tested later in the development process. With this goal in mind these requirements can be defined in sufficient detail following different specifications available, such as CISU-R (Common Industry Specification for Usability - Requirements) developed by the USA National Institute of Standards and Technology. (NIST), the PDF version of the specification can be found here.

Talking about quality, there is a concept called "Quality in use", this type of quality is measurable during the effective use of the software product by its users. It is defined as the capability of the software to allow meeting specific goals with effectiveness, efficiency and satisfaction.

With usability specifications can be provided concrete objectives for usability plus usability criteria that can be tested. More information on setting criteria for effectiveness, efficiency and satisfaction can be found in ISO 9241-11: Guidance on usability, and ISO/IEC 9126-4: Quality in use metrics ("Quality in use" is defined in a similar way to "usability" in ISO 9241-11).