What are the pros/cons of performing usability testing with multiple participants simultaneously?

1. Which test cases can be performed for application with multiple users?
2. Why you should test with 5 users?
3. How many participants do you need for most usability tests?

Which test cases can be performed for application with multiple users?

Concurrent or concurrency testing technique is done to detect the defects in an application when multiple users are logged in.

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.

How many participants do you need for most usability tests?

In summary, research suggests that from three to twenty participants can provide valid results, and a good baseline is between five and ten participants. In general, there should be more participants for more complex, highly critical projects; while fewer participants are necessary when testing more novel designs.