Rocky Agrawal:
Counting registered users instead of daily active users tells us nothing about the popularity of the service. Think of the millions of people who’ve registered for Google+ but never use it. Second, given the huge popularity of Google search, Gmail, and YouTube, it’s actually surprising that so few people who have registered for Google+ are using those more popular services on a daily basis — only 60 percent. After all, remember that a lot of Google+ users accidentally became Google+ users only because they were already attached to another Google service.
It’s always confused me whether or not Google+ is an “opt-in” service. It is, on the one hand, because you must click “join” to start plussing. But it isn’t, on another hand, in that you can +1 things with a Google account.
And what is “active” anyway? Liz Gannes for AllThingsD:
The thing is, Google envisions Google+ as a binding layer between all its products, rather than a discrete entity. While Gmail may have 350 million active users, as Page disclosed today, it’s not so easy to split out Google+.
The blurry numbers do make some sense. For instance, Google+ content will now show up in an increasing amount of search results for signed-in Google users. How do you count that?
So really, we can’t get an exact count of engagement since Google+ is not an island, its a platform on top of Google.
The better question to ask would be, “How many people are making stream updates?” Of the supposed 100 million people, I suspect that 20-30% of Google+ registered users engage in their streams daily (or hangouts, or whathaveyou). But we can’t really know for sure.