The New York Times ran a story headlined “Study Shows Marathons Aren’t Likely To KillYou,” claiming that the risk of dying on a marathon is twice as high if you drive it than if you run it. The underlying study

(Redelmeier and Greenwald 2007) estimated risks for running marathons and for driving. The measure of risk was deaths per day. The study compared deaths per day from driving on marathon days to deaths per day from driving on control days without marathons. The rate on marathon days was lower. (Roads are closed during marathons; control days were matched to marathon days on day of the week, and the same time periods were used; data on traffic fatalities were available only at the county level.) The study concluded that 46 lives per day were saved by road closures, compared to 26 sudden cardiac deaths among the marathon runners, for a net saving of 20 lives. What’s wrong with this picture?

Comment first on the study, then on the newspaper article.