The metric that matters. Pay attention.
Look for hand-raisers. These people are the passionate ones. These might become the next set of leaders.
Q. Can you tell me your name, where are you from and a few sentences about yourself?
Q. How did you hear about this community?
Q. Why did you want to be part of it?
Q. What, if any, community activities do you participate in?
Q. What do you get out of participating?
Q. What do you enjoy most, and why?
Q. What's frustrating, and why?
Q. Are you interested in participating more in the community? What would you like to do?
Q. If you could wave a magic wand and summon any tool or resource for community members like yourself, what would you ask for?
Q. What other questions should we have asked?
Q. Anything else you'd like to share?