Tree Testing - Participant Size

[christa K]

Hi community! I'm hoping you can share your approach/best practices for determining the appropriate size of participants in an unmoderated tree test study. 

I'm also planning to supplement with moderated focus groups but with limited users (5 per region) to gather more qualitative data. 

I would love your insights or lessons learned on this topic. Thanks

[Emil Alex]

Hi Christa, 
The last time we did a tree test for the out-of-the-box taxonomy for the Unified Employee Portal, we ran the study with 100 participants. This was determined based on the complexity of the taxonomy that we were testing, which took into account the number of categories (5), sub-categories (33) & use-cases being tested (45). 
Although there isn't a set formula for defining the exact number we were able to determine a sample size based on previous studies where we could see patterns emerge. We had done an open card sort with 274 participants (unmoderated) and a closed card sort with 29 participants (moderated) before this study which helped inform our approach for the tree test. 
Supplementing this with moderated focus is a really good idea. I hope this information helped.

[christa K]

Thanks, Emil. Yes, this is helpful!