There Is No Set Formula to Determine an Appropriate Sample Size for Qualitative Research.

Qualitative researchers care more about data saturation than sample size. This makes it difficult to estimate up front how many samples or participants will be necessary for a qualitative study.

Seaman and Yocco have each suggested that the number of users interviewed may vary depending on factors:

  • the scope of the project, meaning the extent to which the results will be applied, will have the greatest bearing on the sample size; a familiar problem space will require fewer participants than an unfamiliar one
  • the diversity of participants will increase the number you need to sample
  • the experience of the researcher may reduce the required sample size

Related

Citations

Seaman, Mitchel. “The Right Number of User Interviews.” Medium (blog), October 5, 2015. https://medium.com/@mitchelseaman/the-right-number-of-user-interviews-de11c7815d9.

Yocco, Victor. “Filling Up Your Tank, Or How To Justify User Research Sample Size And Data.” Smashing Magazine (blog). https://www.smashingmagazine.com/2017/03/user-research-sample-size-data/.


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