Human factors and cost benefits
1.3 Human-centred design and systems engineering
The discipline of ergonomics or human factors places humans as the centre of attention in system development. Systems cannot be considered to be truly integrated without the appropriate matching of users (not forgetting maintain- ers), the technology or equipment they will use, and the environment within
which the equipment will be operated. Taking people into account in this way, by means of human- or user-centred design, has long been a cardinal principle for human factors and this is now enshrined within the national and interna- tional Standard BS EN ISO 13407 ‘Human-centred design processes for interactive systems’ [3].
This Standard provides guidance on the human-centred design activities that take place through the life cycle of interactive systems. Although the Standard was origi- nally written with special reference to computer-based systems, it is readily applied to any other type of system. In Clause 4 it stresses that making interactive systems human-centred brings substantial benefits by increasing usability and such highly usable systems:
• are easier to understand and use, thus reducing training and support costs;
• improve user satisfaction and reduce discomfort and stress;
• improve user productivity and operational efficiency of organisations;
• improve product quality, and provide a competitive advantage.
Arising from this, in Clause 5 the Standard lays down four key principles for the human-centred approach to design:
• encourage the active involvement of users in design, and clearly understand the user and task requirements;
• establish the appropriate allocation of functions between users and technology;
• iterate design solutions;
• adopt a multi-disciplinary approach to system design.
These principles, more than any others, underpin the foundations of human factors and ergonomics. They represent the key tenets of the science, and human factors tools and techniques such as task analysis (see also Chapters 5 and 8), workload assessment, and job and team design can each be linked to one or more of those tenets.
However ’twas not ever thus! As will be seen in Chapter 2 there was a time, some 40 or so years ago, when the opportunities and prospects for technology began to offer much, especially in the defence sector. But the benefits that could be delivered to users seemed to fall short of these expectations. It soon became clear that there was an inef- fective match between the technology, the users and their operating environment, and the methodology known as MANpower and PeRsonnel INTegration (MANPRINT) was introduced within the US Department of Defense as a means to assist in achieving the most effective match. Subsequently adopted within the UK Ministry of Defence, and then revised and re-named Human Factors Integration (HFI) for broader adoption in the defence and civil sectors of industry, these two programmes have done much to encourage the adoption of the human-centred approach within complex equipment design.
The Standard BS EN ISO 13407, is derived from, and links to, what can be termed a most important ‘umbrella’ Standard. This is the recently published Systems Engineering Standard BS ISO/IEC 15288 [4]. This Standard provides a common series of processes and a unifying framework covering the life cycle of all systems from their conception through to retirement and disposal. Most importantly
the framework can be ‘tuned’ appropriately to suit any organisation’s particular needs in terms of its overall purposes and the outcomes that it is aiming to achieve. Within BS IS EN 15288 the varied life cycle processes are described in terms of four types of process groups and it is from these that processes can be tailored to suit the individual needs of organisations, their structures, functions and stakeholders. Many organi- sations have derived their own life-cycle stages which themselves derive from the generic life-cycle stages tabulated in 15288.
Together with 15288 and 13407 there are two additional documents and collectively these form an important ‘quartet’ of related standards:
• BS ISO/IEC 15288
• ISO PAS 18152
• BS EN ISO 13407
• BS ISO/IEC 15504
As noted above, 15288 provides the total spectrum of processes covering the life cycle of systems. From this framework 13407 has been derived so as to provide guid- ance on the human-centred design activities that take place throughout the life cycle of interactive systems. The third document, ISO PAS (Publicly Available Specification) 18152 [5], is intended for use in process risk assessments (also known as Capability Maturity Modelling) and it has been carefully structured to show the links between 13407 and the fourth document BS ISO/IEC 15504 [6]. In this way we haveHuman Factorsprocesses (as contained within the PAS) expressed in a manner completely analogous withSoftwareprocesses (15504) and all are derived from the over-arching, common, framework of 15288.
It is important to note that within the wider context of the engineering frame- work of life-cycle processes HFI can be considered as only one of several related, methodologies contributing to system acquisition; each is related insofar as they contribute to the processes of the system life cycle. Thus many engineers will be familiar with the through-life management programmes known as Integrated Logistics Support (ILS), intended to provide in-service support at the optimum whole life cost, and Availability, Reliability and Maintainability (AR+M). These various methodologies of HFI, ILS and AR+M inter-relate strongly and each has a complementary role to play within system development. Scheduled and resourced appropriately they vividly demonstrate the seamlessness of operability, maintain- ability and availability throughout the system life cycle. Thus, for example, operability does not end when maintainability and/or availability starts or vice versa because each contributes in various ways to the evolution of system design. A good example of the manner in which they seamlessly contribute to one another can be found with the ILS Use Case Study. Amongst other things this may contain user role and activity descriptions that can also be used within the HFI methodology to assist with the evolution and development of Target Audience Descriptions (TADs). The TAD is the means by which a picture of the skills and capabili- ties, and the associated training regimes, can be put together for design and other engineers.