One thing I do is to start a list of observations or issues after the first two or three participants. I go over this list with my observers and get them to help me expand or clarify each item. Then we agree on which participants we saw have that particular problem.
I continue adding to that list the numbers for each participant who had the issue and note any variations on each observation.
For example, in a study I’m working on this week, we noted on the first day of testing that
Participants talked about location, but scrolled past the map without interacting with it to get to the search results (the map may not look clickable)
I went back later and added the participant numbers for those who we observed doing this:
Today, I’ll add more participant numbers. At the end of the study, we’ll have a quick summary of the major issues with a good idea of how many participants had each problem.
Participants talked about location, but scrolled past the map without interacting with it to get to the search results (the map may not look clickable) PP, P1, P3
There are three things that are “rolling” about the list. First, you’re adding participant numbers for each of the issues as you go along. Second, you’re refining the descriptions of the issues as you learn more from each new participant. Third, you’re adding issues to the list as you see new things come up (or that you didn’t notice before, or seemed like a one-off problem).
I will still go back and tally all of the official data that I collected during each session, so there may be slight differences between these debriefing notes and the final report, but I have found that the rolling issues list and the final reports usually match pretty closely.
Doing the rolling list keeps your observers engaged and informed, helps you cross-check your data later, and gives designers and developers something to work from right away that is fairly reliable.