You are here: Toolkit home » Knowledge & tools » Evaluation tools » User involvement - Participants

Different stages in the design process require different kinds of information, so the most appropriate users to involve and how to involve them may vary from stage to stage.

Involving large numbers of users improves accuracy but can be expensive. Useful feedback can be obtained from smaller numbers of users. In practice, within a single category of users

• The majority of problems can be identified with 10 users
• At least 3 users of any one type are needed to reduce biases from user responses and observations

Various organisations can provide access to users.

• Ricability www.ricability.org.uk
• User associations, such as the Royal National Institute for the Blind, Royal National Institute for the Deaf, and Help the Aged

The types and aims of user involvement

Who to involve?			Aim
Broad user mix	-	Users from a range of market segments	To understand general user requirements
Boundary users	-	Users on the limit of being able to use the product	To identify opportunities for design improvement
Extreme users	-	Users with a severe loss of capability	To inspire creativity during concept development
Mixed experience users	-	Users with different levels of experience with similar products	To understand the impact of experience on use
Community groups	-	Groups of users who share experience of interacting with similar products	To provide a broad understanding of product use