Leetaru used a database of 100 million news articles spanning the period from 1979 to early 2011. The data is from the Open Source Center and Summary of World Broadcasts, both set up by the U.S. and British intelligence agencies to monitor what amounts to nearly every news source in the world, and translate them into nuanced English. By analyzing the text in the news stories and the tone — whether they were largely positive or negative — Leetaru found that patterns emerged that seem to line up with major periods of unrest. For example, in Egypt, the tone of news articles about Mubarak grew increasingly negative as the protests grew, until eventually Mubarak resigned.

It isn’t just the tone, howvever — it’s also the change in tone over time. Saudia Arabia’s government has remained in power, becuase the tone of the news there has been equally negative before, whereas Tunisia and Egypt hit new lows. Leetaru notes that many of the country experts on Egypt said Mubarak would likely ride it out, as he had done before.