The NSA is on a hunt to find terrorists—but when it sorts through American communication records to find them, what is their accuracy in identifying one? How often do they come up with “false positives?” This is an erroneous ‘positive’ diagnosis resulting from testing inaccuracies. While the NSA test will accurately measure 99 percent of terrorists who take it, it’s not true that 99 percent of ‘positive results’ are terrorists.
There were 207 attempted terrorist attacks within the United States between 2001 and 2011, which is an average of 20.7 per year. If we assume there were 20 individuals involved per attack, that would mean there are 414 terrorists in America per year. Given these numbers, there’s roughly one terrorist out of every 624,927 Americans. Now, with some help from Bayes Theorem, we can say there’s a 99.98416 percent probability that someone is not a terrorist given a positive test result. Stunned? The higher the rarity, the more false results—even despite an accurate test.
Always remember this important rule: when it comes to living online, never say anything (NSA)! For more helpful information, check out this infographic presented by TopComputerScienceDegrees.com.