Dread Risk, September 11, and Fatal Traffic Accidents: An Example of the Ecological Fallacy?

• Main Author: Oliver Kuss
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Greenland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.652.5305; http://www.oliverkuss.de/science/publications/Kuss_Gigerenzer_Ecological_Fallacy.pdf

In a recent article in this journal (Gigerenzer, 2004) Gigerenzer stated that more people lost their lives due reduced air travel and subsequent increased road traffic after the terrorist attack of September 11 than were killed in the four fatal flights. He observed with figures from the national air traffic and road transportation authorities that (1) Americans reduced their air travel and (2) numbers of vehicle miles driven increased after the attack. His conclusion was, that the also observed increase in traffic fatalities was due to many Americans avoiding the risk of flying and driving the unflown miles instead. We fear, however, that the design of Gigerenzer’s study was not suitable to check his hypothesis. Specifically, he is in a certain risk to commit an ecological fallacy, which is the error of judging from aggregated data to individual effects (Rothman & Greenland, 1998). Translated to Gigerenzer’s study that means that we can not be sure that the increased numbers of traffic fatalities are actually caused by people driving instead of flying unless we analyse the individual fatalities. Increased traffic incidents may also have been caused by other phenomena, for example by generally