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What Are the Odds That You Understand Odds?
Katniss Everdeen would have increased the odds of being ever in her favor had she attended the World Science Festival’s “Wizards of Odds” program, a look at how probability can be helpful—and sometimes misleading. The event began with a short film that included an example of the latter. Suppose one in 10,000 people visiting a particular tropical area for a week get Dengue fever. There is a test for Dengue fever that is 99.9% accurate. So if you test positive, that means you are doomed, right? Not necessarily. If all 10,000 visitors take the test, on average one person should be positive and 9,999 are negative. But if the 9,999 healthy people take a test that is 99.9% accurate, there should be 10 false positives. Add that to the one true positive and you get 11 positives, only one of whom is actually positive. So if you test positive, your odds of being sick are actually one in 11 or 9%.Read More