Thank you for bringing this to our attention. After careful review, I also was not able to find the answer to how Health Indexes - Activities and Health Indexes - Index is calculated. After discussing this with several members of the company, I received the following explanation:
we have not made significant R&D investment in the global community health reports (activities & index) in several years. Rather, our efforts have been focused on Community Analytics with emphasis on Engagement; these reports highlight how engaged members are in your community and with other members. They shed light on what members are doing when they are active in your community and are robust substitutes for the "Activities" index you referenced in your email. We have a series of these reports available that can present a compelling picture of the health of your community, including global reports for
- Engagement Ladder, Engagement Index, and Engagement Index by User Type
- Participation Ladder
- User-to-user interactions
- Daily Average User/Monthly Average User (DAU/MAU) report
I'm sorry that I do not have more thorough information to provide with this feature of the CMR.