If you don’t know sociometry, you don’t know groups. Insulting isn’t it? The short test for group knowledge is to ask, “Can you specifically explain how individuals, unknown to each other and from different walks of life are formed into a group?” How's that for a challenge?
Can you find that information in any group counseling textbook?
Near the end of a recent workshop, a trainee said, "No wonder it was a good group, several members knew each other."
What was not understood was that: Members may know each other, but don't disclose very personal information unless all in the group have reached a certain trust level. "...all in the group" includes people who knew each other and those who knew no one.
Bringing any group to a trusting level is done because of attention to sociometry.