Last month, The Guardian delivered a “seismic” piece of news that got publishers everywhere to rethink the value of social traffic when it announced that Facebook had overtaken Google as its primary source of traffic. Today, we have another example of Facebook’s traffic-driving prowess, this time in the e-commerce sector.

Eventbrite sent us a breakdown of its social traffic, analyzing how Twitter stacks up against Facebook against LinkedIn in generating sales leads. The take-away: there is a measurable “value per share” ratio that can be pulled from the data of referrals generated off Facebook, Twitter and LinkedIn. In other words, a Tweet, share or LinkedIn referral is more likely to lead to a sale for your event.

Here’s how Eventbrite breaks it down:

Here’s how they explain it:

We see an interesting divergence between social networks. If we convert all the numbers to Pounds Sterling, we see that the social commerce impact from Facebook is actually stronger in the US, while Twitter and LinkedIn are stronger in the UK. The Facebook social commerce ratio is .041 while in the US it is .064. In other words, a Facebook share in the US, is 56% more impactful. Twitter is almost 10% more impactful in the UK than the US, while LinkedIn is 95% more impactful in the UK.

Editor’ Note: We’ll be digging into metrics and social commerce drivers like this at Social Media Influence 2012. Come join us!