Hey Dan G and Analytics team, I wanted to continue and finish the discussion that happened during the Analytics showcase earlier today. We're implementing a new feature in Wikimetrics where you can upload a cohort and check a box so that every user's accounts on other wikis (projects) will be added to the cohort (using CentralAuth). The purpose is to see if editors are active on other projects. The research scientists pointed out that there are issues with CentralAuth and they are showing up in EventLogging ( https://bugzilla.wikimedia.org/show_bug.cgi?id=66101 ). Let me try to sum up the issue here: Suppose someone has an unattached account. She then went to an editathon and volunteered her name to be included in a cohort. The resulting cohort when expanded with CentralAuth would include users from other wikis. Dan pointed out that this would be extremely unlikely that a cohort expanded using CentralAuth would include unattached users. I'm inclined to not worry about the issue and move ahead with releasing the feature. Please discuss I'm missing something.