After reading the article, “Know Your User – UX Statistics and Insights” by Designer Miklos Philips, I thought it would be interesting to expand beyond understanding your users to include the number of participants needed for various research initiatives.
The original premise of Miklos’ article was to include an infographic of the knowledge. Some of the most memorable UX concepts exist as stand-alone pieces and have helped generations of designers understand complicated principles. Take for instance “The Elements of User Experience” created by Jesse James Garrett over 18 years ago, or the “10 Usability Heuristics for User Interface Design,” developed by Jakob Nielsen over 23 years ago! Both concepts have so many adaptions a family tree of variations is possible.
In the spirit of visualizing data, I have designed an infographic to show the ideal number of users needed for various types of research methods.
It should be known that while conducting research there is an optimal number of users needed based on the type of research performed. Unfortunately, this knowledge is scattered across the web. NN/group holds much of the information on qualitative and quantitative studies, while SurveyMonkey has an excellent survey sample size calculator. Here is an infographic to make much of this knowledge readily available in a visual format.
Nielsen, Jakob, and Landauer, Thomas K.: “A mathematical model of the finding of usability problems,” Proceedings of ACM INTERCHI’93 Conference (Amsterdam, The Netherlands, 24-29 April 1993), pp. 206-213.
Tullis, Tom, and Wood, Larry. (2004) How Many Users Are Enough for a Card-Sorting Study?, Usability Professionals Association (UPA) 2004 Conference, Minneapolis, MN, June 7–11, 2004.
Nielsen, Jakob. “Quantitative Studies: How Many Users to Test?” Nielsen Norman Group, 26 June 2006, www.nngroup.com/articles/quantitative-studies-how-many-users/.
Nielsen, Jakob, and Kara Pernice. How to Conduct Eyetracking Studies. Nielsen Norman Group, 2009, How to Conduct Eyetracking Studies, www.nngroup.com/reports/how-to-conduct-eyetracking-studies/.
Guest, Greg, et al. “How Many Focus Groups Are Enough? Building an Evidence Base for Nonprobability Sample Sizes.” Sage Journals, vol. 29, no. 1, 28 Apr. 2016, pp. 3–22., doi:http://journals.sagepub.com/doi/10.1177/1525822X16639015.
“Sample Size Calculator: Understanding Sample Sizes.” SurveyMonkey, www.surveymonkey.com/mp/sample-size-calculator.