KentuckyFC (1144503) writes "One of the most widely shared tweets in history is Obama's "Four more years", posted after his second presidential election victory and currently retweeted 775,000 times. But how would different wording have influenced this tweet's popularity and the way it spread? It's easy to imagine that there's no way of telling what might have been in such an alternative universe. But a surprising phenomenon on Twitter has allowed data scientists to study this kind of alternative reality and work out the factors that make one tweet more popular than another. It turns out that the twitter stream contains a surprisingly large number of tweets from the same authors, pointing to the same content but with different messages. That's a natural experiment in which factors such as the author, the URL, the number of followers and so on are all held constant while the message varies. By studying these pairs of tweets, researchers can measure how well each performs and then determine which factors contribute to their popularity. These turn out to be things like the amount of information the tweet contains, the language it uses and even whether it includes a request for a retweet. The team has developed an algorithm that predicts which of a pair of tweets is more likely to be successful with greater accuracy than humans. And they've even set up a website where anybody can test their tweet-rating ability and thereby improve their chances of writing the perfect tweet."