Zarella examined a dataset of more than 1.2 million random tweets to find correlations between the use of non-alphanumerical characters and the number of retweets. His analysis found two characters with particularly strong correlations: hashtags and quotation marks.
While not quite as impactful as hashtags, quotation marks also dramatically improved a tweet's chances of getting retweeted.
Zarella found tweets that included quotation marks were 30% more likely to be retweeted than those that did not.
In a separate analysis, Zarella examined a dataset of more than 450,000 randomly selected tweets to see how using each of the four most popular ways to post images to Twitter affected retweets:
- Tweets with images posted via Twitter's own, native image uploading service (pic.Twitter.com) were 94% more likely to be retweeted than tweets with no image links.
- Tweets with Twitpic links were 64% more likely to be retweeted.
- On the other hand, tweets including Instagram links were 42% less likely to be retweeted.
- Tweets with Facebook image links were 47% less likely to be retweeted.