If you want to know what’s up with the flu at the moment, you have a few choices: You can get the latest information at . Or you can get the from the Centers for Disease Control and Prevention, which is based on data that’s by now a couple of weeks old.

But a in the journal Science finds that quicker isn’t necessarily better.

This story started in 2008, when scientists at Google realized that they could measure flu activity by tracking when people searched for flu-related terms. They created a handy site called Google Flu Trends. And it works pretty well — some of the time. But don’t bank on it.

“It missed by a huge amount last year and actually, it turns out, it’s been missing by a fair amount for several years,” says David Lazer, a professor of political science and computer science at Northeastern University. He says Google Flu Trend whiffed during the 2013 flu season.

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