> Also, the 5 number in the headline is just misleading, since he clearly points out that the real number is 15. The 5 number isn't misleading at all, the auth

> Also, the 5 number in the headline is just misleading, since he clearly points out that the real number is 15. The 5 number isn't misleading at all, the author shows that it's the 80/20 point. The first 5 users in your usability test give you 85% of the value of testing with 15. The takeaway is to not do the same exact test with 15 users, do an iteration with 5, and rinse and repeat. "Let us say that you do have the funding to recruit 15 representative customers and have them test your design. Great. Spend this budget on 3 studies with 5 users each!"