The average difference in measured usability between competing websites is 68%. This is smaller than expected, but makes sense given the dynamics of design within individual industries.| Nielsen Norman Group
The average business metrics improvement after a usability redesign is now 83%. This is substantially less than 6 years ago, but ROI remains high because usability is still cheap relative to gains.| Nielsen Norman Group
Testing ever-more users in card sorting has diminishing returns, but test at least 15 users -- 3 times more than you would in traditional usability tests.| Nielsen Norman Group
Several usability findings lead directly to higher sales and increased customer loyalty. These design tactics should be your first priority when updating your website.| Nielsen Norman Group
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.| Nielsen Norman Group
When collecting usability metrics, testing with 20 users typically offers a reasonably tight confidence interval.| Nielsen Norman Group
What users believe they know about a user interface impacts how they use it. Mismatched mental models are common, especially with designs that try something new.| Nielsen Norman Group