The researchers POSIX group is not needed anymore, people that still need access should be placed either into analytics-users (for simple access) or analytics-privatedata-users (for Hadoop/data/etc.. access).
The only thing that the group grants at the moment, other than stat100x ssh access, is read permissions for /etc/mysql/conf.d/researchers-client.cnf on every stat100x host to query the wiki replicas. The same perms are granted to analytics-privatedata-users and we can argue that accessing the wiki replicas can be considered as private-data access. The name of the group is misleading of course, no member of the Research team (or collaborator) needs it for example :)
These are the current users:
researchers: gid: 714 description: Access statistics hosts and also provides access to research mysql credentials. If a user is added to this group it should not need to be in analytics-users or analytics-privatedata-users. In case of doubt, please ask to the Analytics team. More info https://wikitech.wikimedia.org/wiki/Analytics/Data_access#Access_Groups members: [catrope, dduvall, mattflaschen, cooltey, marktraceur, jhernandez, daisy, etonkovidova, legoktm, risler, sbisson, matmarex, nikerabbit, dstrine, jdittrich, debt, mlitn, sharvaniharan, kharlan]
I am going to send an email to these users to clean up accounts not needed anymore :)