We know that most ReTweets contain a link, but there are hundreds of different URL shortening services available to help you save space with that link. I analyzed my database of over 30 million ReTweets and compared them to over 2 million random Tweets to find which shorteners are the most (and least) ReTweetable.
I calculated how much more or less often each URL shortening service appeared in ReTweets than it did in normal Tweets and presented this value as a percentage. For instance, in my data 9.28% more ReTweets than random Tweets used bit.ly. I took into account the fact that ReTweets tend to contain more links than average Tweets and normalized the occurrence values.
The short, post-Twitter shorteners, bit.ly, ow.ly, and is.gd were all more ReTweetable than the older, longer, tinyurl.