Yes, I actually remeber we once had such a KPI (for posts) in one of our older Dashboards - we also used it to review performance in our customer calls. It was called “Sense of community” as it is an indicator of how many engagements / touchpoints with different users someone might have. 

I am not entirely sure why we removed it from the Dashboards at one point, but I could see something like this coming back in the future! I have not seen something like this being done for likes though...

For posts, there is a way to calculate this from our exports: Simply do a post export, then create a pivot table, and in this count the unique usernames per topic title. (Please let me know if you don’t know Pivot tables, happy to elaborate).

This way you can see this KPI per topic, but you can also calculate the average number of contributors to a topic.

The downside of doing it like this: You might skew the data a bit depending on the period that you select. E.g. if you have a two year old topic that only has received a single new comment in the period you selected, it would show as a single-user topic as older posts are not in the export...

Okay, good to know that this will be possible to find out easily in the future.

Thanks for the tip. I am familiar with the Pivots but of course I am looking forward to see this from the Dashboard easily 

The downside you mentioned isnt issue for us but it is good to know and remember.