What makes the Boston Marathon so special? A lot of things: the history and tradition behind the event; the course; the need to qualify. The list goes on and on.
Turns out Boston is also special because the winning time is so unpredictable. Paul Kedrosky has a pair of interesting charts depicting the winning times in the Boston and NYC marathons and the volatility of those results, and they show that while NYC is becoming easier to predict (each year’s winning time varies less and less from the previous year’s winning time), Boston is not. As he explains, “We should expect declining standard deviations over time in these events, with the best athletes only differentiated by small-ish amounts of time. And that is, more or less, what is happening in the New York Marathon, but such is not the case – or at least hasn’t recently been the case – in the Boston Marathon.”
Check out the comments on the post for a discussion of possible reasons for this phenomenon. Front-runner: the weather. Of course, as one commenter points out, Boston’s recent volatility is really only due to one extraneous result, a slow winning time in 2007.