Your questions answered

Still unsure of what user-centred design is and how it is applied? Alison Black answers some common queries

What is the difference between user-centred design and market research?

There can be overlap between the two: both can identify users' expressed, high-level requirements. But market research focuses primarily on understanding the market in general terms, identifying triggers to buy or use products and services and finding acceptable price points. The individual and observational focus of user research makes it possible to identify unexpressed user needs and to create a dialogue with users through iterations of prototyping and evaluation that shape how products and services are developed.

What is the difference between user-centred design and ergonomics? 

There is overlap between user-centred design and ergonomics: both bring a human perspective to product and service development. The clearest difference between user-centred design and ergonomics lies in how the two processes are applied. User-centred design helps designers understand peoples’ existing experience and project forward to products and services people might use in the future. It comes into its own in the exploration of the potential for new products and services as well as in their refinement and development.

Ergonomics tends to come into play after a design brief is formulated, to specify how a new product and service must be designed to fit the physical or cognitive characteristics of its users; and, in some cases, to determine what are the safe limits within which people can use products and services.

User-centred design ranges across the practical, emotional and social aspects of product and service use, in order to deliver concepts that have the potential to engage people and fit with their lives. Ergonomists tend to focus on the practicalities of product and service use, but may also consider the emotional and social impact of their recommendations, since these can influence practical aspects of use.

Is user-centred design the same as 'usability testing'?

No, user-centred design is likely to include usability testing in the latter stages of design development. But a user-centred approach involves engaging with users from the earliest stages of tackling design problems and gathering input and feedback from them throughout the development cycle. On its own, usability testing is unlikely to optimise products for users.

Is user-centred design needed mainly for new-technology products? 

It's relevant to all design development and is used by designers working on projects ranging from environmental design to packaging design. It is, perhaps, described most explicitly in reports of the development of new-technology products (where there tends, anyway, to be more press coverage).

Does design inspiration have to come from users?

Not necessarily, but design ideas need to be developed with user input from the earliest stages. Design programmes should allow for the modifications to initial, inspired ideas that are likely to be needed as a result of user research.

Can an expert review substitute for user research? 

Relying on expert review may deliver only a limited perspective. Expert review is particularly vulnerable in the design of complex products and services, intended for a wide range of end-users, whose perspectives differ from those of the reviewer.

How many people should be researched?

Getting a spread of different types of user (or potential user) is more important than weight of numbers. Observational research yields a large amount of data and there is no point in observation if there isn't adequate time to analyse the data generated. Typically, depending on the complexity of the project, 10-15 people are observed.
Evaluation should, again, ensure coverage of different types of user.

There has been debate about the number of people needed in evaluation. Some practitioners argue that few new insights result after evaluation with five users of the same kind. Others argue that crucial information can be missed if only five people are involved in evaluation. A good starting point would be to evaluate with five people from each intended user group. If there is substantial overlap in response from each group, there may be no need to test further.

How can looking at behaviour today help design for tomorrow?

It is a challenge to identify thematic human needs that are likely to endure over time (for example, the 'need' for text messaging among teenagers, although easy to explain, would have been hard to predict). User-centred designers use research data as a basis for projecting future need. They build scenarios for future products and services and test them with users in order to assess their potential. There's no guarantee in user-centred design, but there is a greater likelihood that products or services developed through the process will meet future need.

What is the difference between user-centred design and inclusive design?

Inclusive design is an approach which ensures that the full spectrum of user needs, including the needs of people with disabilities, is considered and accommodated in the design response. User-centred processes are essential to inclusive design, both to understand the reality of people’s lives and to evaluate products and services as they are developed to ensure they are genuinely inclusive.