A survey of European IT developers (Maguire and Graham, 1996) suggests that concern over user issues is widespread. 91% of respondents felt that user and organisational issues are important and 58% felt that they did not address these issues properly. An international study (Hefley, 1996) indicates that while 70% of organizations use a process for managing product quality, only 32% explicitly addressed usability as an integral part. Thus, 68% of the organizations either do not follow a process for managing quality or do not address usability as an integral part. Of the organizations surveyed, only 11% always integrate their process with their overall product creation process. Only 36% of the organizations surveyed follow a defined process that explicitly addresses usability/ease of use as an integral part of this process.
Even when usability is addressed it is rarely approached in the right way. Hakiel (1998) reports the software industry's current (misbelief) that improvements in practice are achieved by simply extending the repertoire of software engineering methods to include Human Computer Interaction (HCI) methods.
Problems deriving from this restricted approach to usability are avoided by taking an extended view of usability which subsumes utility (utility being the functions to be provided to the user) and shifts the focus from the development of software to the development of systems. This is because the system functions provided to support user tasks contribute about 60% of the ease of use whereas the specific design of user interfaces to software contributes only 10% (IBM, 1992). Activities concerning the identification and specification of such functions from the end user's point of view should therefore be part of the overall design process. Adopting an extended view of usability implies a substantial, if not radical, change in the role of HCI/Usability engineering in the design of software-based products. Under this approach, specification of function cannot be considered to be simply a software engineering activity and must be based on considerations relating to disciplines quite different from those on which software engineering is based.
The HS model builds on a line of standards development and a brief summary of the background is appropriate. Development might be considered to have begun with ISO 13407:1999 Human-centred design processes for interactive systems, which, amongst other things, sets out the principles of Human Centred Design (HCD) and defines the activities required to develop equipment in a user-centred manner. The principles of HCD are:
- The active involvement of users and a clear understanding of user and task requirements;
- An appropriate allocation of function between user and technology;
- Iteration of design solutions;
- Multi-disciplinary design.
ISO 13407 brought about an industry-led effort to formalise software and equipment HCD, resulting in the Usability Maturity Model (UMM) in ISO TR 18529:2000 Ergonomics of human system interaction - human-centred lifecycle process descriptions. The process descriptions are compliant with the ISO process assessment framework.
The UMM has found widespread acceptance and a measure of validation. The background to this line of work can be found in Earthy et al (2001). Since then, the UK Inland Revenue gained Central Government Beacon status in 2001 for its work using the UMM.
Although the HCD model was initially developed as an assessment tool, it has, like equivalent software process models, found other uses. There have been considerable international efforts recently to consider it as the basis for competence definition for usability professionals.
Operability Assurance for Total Systems
The success of the endeavour at an equipment or product level led to an MOD-sponsored project to build an equivalent model at the level of a 'total system' covering people, technology and organisation. The aim was to extend the MOD's ability to conduct Capability Evaluation from software and system engineering into HSI. That project, together with subsequent development, has resulted in the HS model. The HS model provides an objective, structured way of providing assurance of operability before resources are committed. It also provides a mechanism for improving HSI processes and a means of mitigating project risk.
The approach taken to the development of the model was user-centred. Several iterations were made, building on the extensive comment on earlier drafts; including many constructive comments and proposals from the US HSI community, both informally during model development and then through the international standardisation process.
Again, the precision required of an assessment model has led to recognition of other potential uses, such as planning and competence definition.