Itqualityassurance
- How many participants should I test with?
- How many test users are enough to discover all problems?
- Why you should test with 5 users?
- Why 5 participants in qualitative research?
How many participants should I test with?
Summary: Elaborate usability tests are a waste of resources. The best results come from testing no more than 5 users and running as many small tests as you can afford.
How many test users are enough to discover all problems?
Nielsen's work suggests that 15 users will reveal all the known usability problems in a design, but recommends a more effective spend of three iterative tests with 5 users. Perfetti & Landesman (2001) suggest that more than 8 testers are needed to detect all usability issues.
Why you should test with 5 users?
In a research study from 2000, Jakob Nielsen and Tom Landauer found that you only need 5 users to test your application in order to identify 75-99% of all usability problems. You only need 3 to 5 users to identify the majority of usability issues.
Why 5 participants in qualitative research?
That the probability of someone encountering an issue is 31%
Based on these assumptions, Jakob Nielsen and Tom Landauer built a mathematical model that shows that, by doing a qualitative test with 5 participants, you will identify 85% of the issues in an interface.
