Hey Sara, good question. I think it’s important to start with business objectives - what is the goal of the community? Ticket deflection? Brand advocacy?
That will define which metrics make the most sense to track.
Regardless of the above, the one that I recommend everyone tracks is DAU/MAU (or stickiness). That demonstrates how frequently people come back, which is primarily indicative of health. Aim for 20-30%.
Our latest blog post might also be interesting: A Strategy For Making the Most of Community Health Metrics