I use bit.ly on all of my Twitter tweets. I also downloaded the bit.ly Firefox extension so I can hover over each link and it will show how many clicks were made. The problem is, the bit.ly number is off compared to Google Analytics. bit.ly will says I had 10 clicks (for example), but GA shows a way lower number. Does anyone have an opinion on this?
GA would likely be lower because some users/browsers are either blocking javascript or using ad block add-ons that block GA. In other words - GA is only going to track if the client browser decides to load and run the GA/urchin javascript. And some clients wont! But bit.ly is tracking based on actual clicks on their short links, and in that case the client browser MUST hit bit.ly to follow the link. So I think the bit.ly stats will be more accurate and trustworthy in this case.
If you try lo.ly as a url shortener/ twitter tracker, you'll see it breaks down the clicks into bots and 'humans', and tells you what bots they are. I'd recommend anyone using twitter try it just a few times, because I think you'll be surprised at the results - up to two thirds of the clicks on any twitter link is likely to be bots