Google Reader never had many users. Feedly claims to have captured 80% of the Reader userbase when it shut down, and they have 15 million users. That is incredibly small by the standards of social networks, much smaller than even the pessimistic active-user estimates for G+.
The number of active G+ accounts -- publicly posting in any given month -- is less than that. I and Eric Enge, he of Stone Temple Consulting, have independently estimated this based on G+ sitemap sampling. I pulled about 50k profiles off a single sitemap, Enge 500k from multiple. My pull was based on strong evidence that the profiles are randomly distributed through sitemaps. Both of us found ~6-12m publicly active profiles.
Among my thoughts: the group of people really discussing things online just isn't that big.
Reader was far more significant than Google realised.
That is a bad definition of "active," particularly considering that the original selling point of G+ relative to Facebook was its privacy controls (circles). I know many people who post to G+, only a few of whom do so publicly.
Both Enge and I address both the definition of "active" and of "invisible" non-public activity.
1. We're limited to directly observable public actvity. Given the sitemaps providing a population of profiles to sample, that means looking at actual public posts. Anything else would be Making Shit Up, which I prefer not to do.
2. It's possible get some sense of non-public activity by looking at followers and views for profiles with and without public activity. Evidence is that profiles without public posts have about 4.3% of the activity of those with. That gives roughly 4% of the total G+ userbase, or about 95 million users.
Again: showing activity at any time. That about doubles the active users count in total. (112 million + 95 million). It doesn't speak to recent activity, though.
Feedly probably isn't claiming those numbers with any basis in reality. In particular, many people made Feedly accounts in a hurry out of panic when the shutdown was announced. Having used both, I highly doubt users of Reader are still regular users of Feedly.
I'm a former Reader user and now use Feedly. What do you use that's better than Feedly? I settled on it since it was "good enough" but I haven't invested the time to explore other options.
I always wonder what would be the active-user count for G++ without YouTube (i.e. every logged in Google user visiting a YouTube page is marked as an active G+ user if she scrolls down the page once).
