You could try to use a reference selector. In the tab "selectable objects" you can specify the following Xpath:
[System.UserRoles = '[%UserRole_Analyst%]']
This way you will get a list of analysts to select from.
Hope this helps. If not let me know!
Good luck!
Assuming your users are a specialization of System.User, you should be able to set the Source or your dropdown to XPath and the XPath constraint to
[System.UserRoles = '[%UserRole_Analyst%]']
However, I would recomment you create you own 'Team' or 'Group' entity to link to users, rather than the built-in userrole as it gives you more flexibility over access permissions, etc.