14 DAY TRIAL // Paul Allen, founder of Ancestry.com and serial entrepreneur, has been running a model trying to determine how many Google+ users are out there. He's been updating the estimates with new data and the growth rate is astounding.
While he started out saying that there were 1.7 million users on the social network, he now believes that it will hit 10 million some time today, if not already.
At the current growth rate, providing Google continues to allow users to send out invitations, there could be 20 million people on Google+ by the weekend.
"My surname-based analysis shows that the number of Google+ users worldwide reached 7.3 million yesterday (July 10)... That is a 350% increase in six days," Allen wrote on Google+.
"More impressive than last week's growth is the astonishing growth in users from yesterday at mid-day to tonight -- a 30% jump. My latest estimate tonight shows approximately 9.5 million users. This suggests that 2.2 million people have joined Google+ in the past 32-34 hours," he added.
"I project that Google will easily pass 10 million users tomorrow and could reach 20 million user by this coming weekend if they keep the Invite Button available," he continued.
The numbers rely on several estimates, so they may not be entirely accurate. Allen is very confident in his model though. At the very least, even if the absolute numbers may not be the same, the growth rate is impressive.
Allen uses US Census Bureau data about surname popularity to determine Google+'s size. He uses about 200 rare surnames, to make them easier to track.
When more people with those surnames create Google+ accounts, he extrapolates the data to determine how many US users there are. Previously, he determined that there are 2.12 international users for each US user, which is how he arrives at the final number.
While the math is strong, there are some weak points, the weakest being the US/foreign users ratio. Being that there are no official numbers, though Eric Schmidt said there were millions of users last week, the 10 million figure may not be exact, but it should be a pretty good estimate.