If you happen to be part of of the “test group” for recently launched social network Google+, you might be feeling pretty special right now (not to mention so over Facebook). But with invitations spreading like wildfire, it turns out that the rapidly growing site isn’t all that exclusive anymore.
According to Paul Allen, the founder of Ancestry.com, Google+ had 7.3 million users on Sunday—a 350 percent increase from the 1.7 million people registered on July 4—to approximately 9.5 million users on Monday. The site grew at light speed over the past few days, with a 30 percent jump in membership between mid-day Sunday and Monday night, meaning that 2.2 million people joined the site in just over a day.
By today, Allen estimated that Google+ will reach 10 million users. And if Google keeps the “invite” button available, the site could have 20 million members by this coming weekend.
In order to estimate these membership numbers, Allen used U.S. Census Bureau data about surname popularity in the U.S., and compared it to the number of Google+ users with each surname, splitting the U.S. users from non-U.S. users.
“By using a sample of 100-200 surnames, I am able to accurately estimate the total percentage of the U.S. population that has signed up for Google+,” Allen explained. “Then I use that number and a calculated ratio of U.S. to non-U.S. users to generate my worldwide estimates. My ratio is 1 U.S. user for every 2.12 non-U.S. users. That ratio was calculated on July 4 through a laborious effort, and I haven't updated it since. That is definitely a weakness in my model that I hope to address soon. The ratio will likely change over time.”
Although the model isn’t perfect, Allen said, “I do believe it is quite accurate.” He’s currently testing out a new mathematical formula that could estimate user numbers with 99 percent accuracy, which he’s hoping to include in future models—or, at least, until Google starts officially announcing user numbers.