Initially, Matthew Gerber didn't believe Twitter could help predict where crimes might occur. For one thing, Twitter's 140-character limit leads to slang and abbreviations and neologisms that are hard to analyze from a linguistic perspective. Beyond that, while criminals occasionally taunt law enforcement via Twitter, few are dumb or bold enough to tweet their plans ahead of time. "My hypothesis was there was nothing there," says Gerber.
But then, that's why you run the data. Gerber, a computer scientist at the University of Virginia's Predictive Technology Lab, did indeed find something there. He reports in a new research paper that public Twitter data improved the predictions for 19 of 25 crimes that occurred early last year in metropolitan Chicago, compared with predictions based on historical crime patterns alone. Predictions for stalking, criminal damage, and gambling saw the biggest bump.
"I was surprised," says Gerber. "In the thousands of tweets that I've read, you don't see people saying things like, 'I'm going to rob somebody tonight.'"