Like many large metropolitan areas, Columbus, Ohio has a widespread system of free metro parks. City run parks--mainly reclaimed lands converted to natural areas--located in urban and suburban areas of the city. According to the Columbus Dispatch (headline: Attendance at Metro Parks Droops a Bit), through September of 2008 attendance at Columbus metro parks is down 9% when compared to the same time period last year--4.9 million versus 5.4 million. Bad economy? Population drain?
Nope. The answer turns out to be bugs. One of the park systems 17 parks held an artistic exhibition of wooden bug statues last year, effectively doubling attendance. Attendance returned to normal this year when the bug statues were exterminated. Removing that park from the attendance figures, attendance is down a little more than 100,000 visitors this year or less than 3% (see figures to the right).
Moral: Outliers matter when telling a story with statistics.