Usability expert Jakob Nielsen’s research studying website usability test sizes finds that five users will reveal approximately 85% of usability problems on a website (“Why You Only Need to Test with 5 Users”). This statistic is based on the likelihood that a single user would identify 31% of the problems. If only five users can reveal a majority of usability issues, this statistic indicates that user testing does not need to be extensive or expensive to be effective.
As a designer, I appreciate this statistic because a website’s usability (how easy it is to use) affects the design and ultimately the performance of a digital product. Design aesthetics (visual appeal) is important but means nothing if the product fails to work for the user. Poorly designed websites yield frustrated, disengaged users and low conversion rates. On the other hand, well-designed, user-friendly sites build brand credibility, audience retention and loyalty, and increase conversions.
As a communicator who manages digital properties for a program with scarce resources, I appreciate this statistic because the return on investment is high. Very often, budget is a barrier to testing and optimization. But it doesn’t have to be; one user can discover a third of a site’s usability problems. While five is the optimum number of test users from a cost-benefit analysis, any testing is better than none. “The most striking truth…is that zero users give zero insights,” Nielsen says.
A great opportunity for user testing is in pairing the qualitative data it provides with quantitative data in website optimization. Marketers look to analytics tools like Google Analytics because they offer plenty of easy-to-access quantitative data about who is visiting a website, how they got there and their behavior during visits. User testing can help marketers understand why they see these numbers and how to improve them, leading to informed decisions for site improvements.
Another significance of the feasibility of user testing is the benefit of testing competition. In testing five users, one can easily and cheaply evaluate how websites perform compared to competitors. By learning what others are doing and not doing well, marketers can focus on design changes that will help the site gain a competitive advantage.
Nielson’s study further indicates that a person does not need to be a usability expert to do usability testing or to understand key usability principles. Anyone can gain valuable information and any site can be improved from user testing. Combined with analytics, usability testing and analysis provide context and direction for making findings actionable. Usability testing does not need to be extensive or expensive to provide digital designers and communicators with useful insights to improve the design and efficiency of web products.