Off Topic! - Web Analytics

I'm going way off topic here... but this has been bugging me for a while so I thought I do a post on it.  Yesterday I posted a link on twitter to my Veer Documentary post using bit.ly.  According to bit.ly, by the end of the day (and after two RTs) I had 39 clicks on the link, AKA 39 visits to my blog.

bitly

But then this morning, I check my google analytics, and it says I only had 10 visitors to my site for the whole day, from all sources.

googlyticsSo whether google analytics is counting the bit.ly hits as twitter referrals, or direct traffic, or something else, it's clearly way off.  I guess it's possible that bit.ly is overcounting, but I'd guess the true number is closer to bit.lys considering the combined number of followers for myself, and the two accounts that RT'd the link is 2400.  This article (Is Twitter Sending You 500% to 1600% More Traffic Than You Might Think?) addresses the exact same problem, and the author definitely has a better grasp on the underlying issues than I do... but still can't explain the difference.