With the card sorting method we can enhance usability by creating an information architecture that reflects how users organise content. But how many users should we include in a card sorting exercise?
According to Jakob Nielsen, 15 participants will be enough to reach a comfortable result in most projects. Testing 30 people is better but not worth the money. Going beyond 30 users will hardly improve the results. In projects with limited resources for user research, the remaining users are better spent on qualitative usability tests of different design iterations.
His recommendation is based on results from a study measuring the trade-off curve for testing various numbers of users in card sorting.
- The article Card Sorting: How Many Users to Test
- July 25, 2004
See also: Tips and guidelines (95)