The question is a distraction. Originally, we wanted ten participants for the evaluative test. Then, we doubled the testing by adding another platform — desktop + mobile. So, we reduced the segments, slightly, to two sets of eight for a total of 16, fit into one week with up to four tests a day. By the last test, I felt like I was just keeping a tally of all the things that had already been identified, but were applicable to this participant too, just like the others. Sixteen is a reasonable number of participants, especially with the two segments, but as the researcher I had to wonder if we could have gotten by with less.
The question, “how many participants do we need?” often masks more fundamental issues. For example, they don’t know why people come to their website or what prior circumstances motivates people to go through the funnel. Identifying usability issues will never answer these questions or give them the insights needed to confidently make strategic decisions. I can tell you with precise detail why a certain button was overlooked or misinterpreted, but the participant is only looking at this website because I am paying them — that’s their motivation.
Ask me how many people I need to talk to for a generative study to understand the goals, needs, and motivations of the potential future customer or guest. Ask me how deep we need to go to understand how we can help them solve their problems and be part of the solution that makes their day easier, removing hurdles and obstacles that keep people from reaching their full potential. Ask me how we can make things better.