What is The Half-Life of a Social Link?

It is no secret already that when friends share links via Twitter or Facebook, the links have a very short time to make an impact on other users, before they disappear off the bottom of the average home page or newsfeed.  Now some new research from link shortening brand ly illustrates the point with data; apparently, just three hours after being posted, links have generated pretty much all the traffic they can.

On a post on ly's blog, they explain the persistence of links by measuring something they are calling the "half life" of a link that has been shared across a social network.  By "half life" they are referring to the point in time after posting when the link has received half of the clicks it will ever generate.  Of course, it will generate links after that point - half of its entire links, obviously - but the idea is to stress how quickly it gets to that point.  

For example, ly found that the half-life of 1,000 popular ly links was 2.8 hours on Twitter, 3.2 hours on Facebook and 7.4 hours on YouTube.  

So what? Well, for anyone putting links out there as part of their social media strategy, this is another interesting input into your web analytics arsenal.  If your posts are not generating the traffic you hoped for, look at their timing - are they disappearing before your core audience can see them?