Engineering Approach Illustration: Blandford – Engineering works: what is (and is not) “engineering” for interactive computer systems?

Engineering works: what is (and is not) “engineering” for interactive computer systems?

Ann Blandford

University College London

Dept. of Computer Science, Gower Street, London WC1E 6BT



What does it mean to “engineer” an interactive computer system? Is it about the team doing the work (that they are engineers), about the process being followed, about the application domain, or what? Is engineering about managing complexity, safety or reliability?

Comment 1

Although there are different ways of understanding the engineering of an interactive computer, in all cases engineering would imply the inclusion of design and implementation.

For physical artifacts, it may be possible to achieve consensus on how well engineered a product is, but this is more difficult for digital artifacts.

Comment 2

‘How well engineered’ here is consistent with engineering as design for performance.


In this talk, I will offer some perspectives, both positive and negative, on the nature of engineering for interactive computer systems

Comment 3

See also Comments 1 and 2.

and, at least implicitly, the nature and future of the EICS conference series.

Author Keywords

Engineering; HCI; safety; reliability; professionalism.

ACM Classification Keywords

H.5.2 [Information Interfaces and Presentation]: User Interfaces – Interaction styles.

General Terms

Human Factors; Design; Reliability; Verification.


The aim of this short paper is to facilitate discussion on the role and value of engineering in relation to interactive computer systems.

Comment 4

See also Comments 1 and 2.

It arises, in part, from an activity at the most recent IFIP WG2.7 / 13.4 (User Interface Engineering) working meeting: to develop a short video to communicate the value of engineering for user interfaces. It also arises from discussions I have had with various people on the nature and scope of the EICS conference. Both activities have generated more heat than light. It is, intentionally, not a well engineered argument for a particular position, but a series of vignettes putting forward different cases, for and against particular views of engineering in relation to interactive computer systems (ICS). My intention, which may or may not be realized, is that the community should establish a better shared understanding of the nature, value and role of engineering in the ICS context.

Comment 5

Nature, value and role are critical aspects of engineering. They constitute criteria for the assessment of how well engineering is carried out. See also Comment 2.

If it’s done by engineers then it is engineering

I am a Chartered Engineer. I started my career as a Graduate Trainee Engineer, at about the time the Finniston report [7] was published. That report emphasized the importance of engineering to the future of the economy, and also argued strongly for the status of professional engineers. Within the UK, that is a battle which has now been lost: “anyone in the UK may describe themselves as an engineer. Seeking to regulate or legislate on the use of a now common term is recognized by the Engineering Council as totally impractical.” [6] So, at least in the UK, anyone can call themselves an engineer, and – by extension – claim that what they are doing is engineering. A subset can make a stronger claim: that we are accredited as professional engineers. But is what any of us do “engineering”? Let us consider definitions of engineering.

Engineering: definitions

A dictionary definition of engineering is: “The application of scientific and mathematical principles to practical ends” [14]. The emphasis in the Engineering HCI Community of ACM is on “the application of scientific knowledge and rigorous design methodology to reliably predict and, thus, help improve the consistency, usability, economy and safety of solutions to practical problems” [1]. Both of these definitions focus on principles and rigor for addressing practical problems. Clearly, these principles should apply in the design of complex, safety-critical systems [10]. It is much less clear what it means to engineer the user experience, in terms of fun or affect (a theme in this year’s call for papers). The science of fun is poorly developed, the mathematics of fun even more so. User experience is not so well understood that it can be reliably predicted or delivered consistently without extensive iterative testing, which is standard ICS development practice, and not particular to an engineering approach.

The importance of iteration in iCS

Most HCI text books assert that iteration is essential in the design of ICS. Rogers et al [12] focus on four main phases of developing interactive systems: establish requirements; design alternatives; prototype; and evaluate. Iteratively. Best practice in the development of ICS includes requirements gathering and user testing, neither of which is particularly amenable to the application of scientific or mathematical principles, although both can be done rigorously and are essential to the delivery of systems that are safe and usable.

Tools such as CogTool [13] bring an engineering rigor and prediction to important aspects of user interaction with interactive devices, based on task performance. Similarly, model-based approaches to system development [9] support the task-based development of ICS. However, none of these “engineering” approaches take account of the softer, but equally important, aspects of the use of ICS, including the full user experience, how the ICS fits within its broader context of use, and how people conceptualise the activity the ICS is designed to support [2]. Without taking such aspects of use into account, the engineering of ICS runs the risk of delivering solutions to the wrong practical problems.

A case study: CHI+MED

The CHI+MED programme [5] provides an interesting object of study in terms of engineering ICS. CHI+MED is studying the design and use of interactive medical devices: safety-critical devices such as infusion pumps that are themselves moderately complex, and are used in highly complex settings. There are many aspects of these devices that can be subjected to an engineering approach, including modeling their safety properties [4] and formal verification [8]. Such approaches are necessary, but not sufficient. There are many aspects of the use of such devices in practice [11] that need to be understood and designed for. Without systematic study of the use of devices in context, and rigorous description of the “problem”, which defines requirements for the next generation of systems, and without careful testing of device prototypes, it is easy to deliver solutions that are verified by not validated [3]. There is a risk that by separating off “engineering” approaches to ICS, the engineering becomes distanced from the practical problems that it is intended to address.


There is an argument, based on the above, that engineering is the servant of design – that the user needs are identified outside the engineering process, that the engineer’s job is just to make the design as conceived by others work (ensuring that the system performs as intended – traditionally referred to as ‘verification’). This seems at odds with the broader view of software development lifecycles that development is iterative [3], and is concerned with considerations of usability, utility and experience (all of which are arguably elements of ‘validation’), which should also be concerns for engineering.

The title of this paper, “Engineering works”, is a play on words. One reading is a claim: that engineering makes things better; that it provides assurance that the proposed solution to a problem (an ICS) is well engineered: that it will not crash or permit the system to get into unsafe states, and will manage complexity well. The second reading is as a noun, “works”, qualified with an adjective, “engineering”; engineering work is needed when things have gone wrong, or need maintenance. In the context of EICS, I suggest that both meanings pertain: that engineering can make complex systems work well, but that the engineering approach needs active maintenance to remain relevant to other aspects of ICS design and to avoid becoming narrow and irrelevant.


This paper has benefitted from discussions with many people, but the viewpoints put forward are my own. CHI+MED is funded by EPSRC EP/059063/01.


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