Facebook beats Google, becomes most visited site : really ?

Facebook, riding a terrific wave of growth in its popularity, achieved yet another milestone last week - it toppled Google.com to become the most visited US site as mentioned in the weekly report from Hitwise, an online traffic monitor. Facebook.com had outpaced Google.com in the past as well, but it was only on major festive occasions such as Christmas and New Year. This is for the first time that Facebook has surpassed Google in weekly site visits. The market share of visits to Facebook.com increased 185% last week as compared to the same week in 2009, while visits to Google.com increased 9% during the same time frame. The tremendous growth pace of Facebook can be seen in the graph below.

At this point of time, however, these results need to be perceived with caution due to a couple of reasons :

• Other online traffic monitors such as Alexa, Compete and Quantcast continue to report Google.com as the site receiving the highest number of hits from US.
• The traffic monitoring mechanism of Hitwise is not publicly known, and nor do we know the critically important factor : sample size.
• Since Facebook, due to its inherent nature, is way more sticky than Google.com, a better measure for comparing them would be "number of unique visitors", rather than just "site visits". Also, an increasing number of internet users are doing Google search through either toolbar or other Google services such as GMail, Calendar, Reader, etc. Thus, just the "number of site visits" for Google.com does not effectively capture the popularity of Google search.
• Another big reason for this huge up-surge in the "site visits" to Facebook could be the "share on Facebook" widget which is being increasingly integrated with all the major websites worldwide. Though the action of sharing a link on Facebook requires calling facebook.com(for login), does it really qualifies as Facebook traffic ?

Hence, while there is no doubt that facebook's popularity has been sky-rocketing, and "average time spent per visit" on it is considerably greater compared to Google.com; it is highly probable that Facebook traffic comprises of repeated visits by a smaller sub-set compared to Google.com's traffic composition : less repeated site-visits by a much larger set of users. So, before arriving at any conclusions, we need to ask : are using the right metrics to compare the popularity of these two internet leaders ?