The Slowing of the Kentucky Derby

on May 6, 2011

It is easy to assume that breeders continue to produce faster and faster horses each year. The truth is that Kentucky Derby winners have been slowing down for some time. As you can see, since the 1960’s the winning run has trended (ever so slightly) slower. Of course, the differences in speed we are talking about are far to minute to be perceived, but there is no doubt that the fastest decade on average was the 1960's.

Is this because of continuous inbreeding among thuroughbreds? Perhaps just a fluke of nature that will soon right itself? After all, if you drag the slider back to inception you can see that the trend has been undeniably upwards since the 1870's.


This is an excellent example of how a line can mislead us to believe a trend exists when none actually does. Tableau allows you to quickly determine that the trend line has a p-value of 0.275 by hovering over the line. Therefore, we cannot reject the null hypothesis that the coefficients of the model are zero. So, there is insufficient evidence to conclude that races are getting slower. If we dug deeper into the description of the model, we would see that the coefficient for the intercept is significant but the one for the slope term is not. So, given only information about the speed of past races, our best prediction of the speed in future races is the average speed of past races.

The classic narcissistic tendencies are a highly inflated sense of self, a display of confidence, omnipotence, and uniqueness, such as ‘I am better than everyone else’ which may seem to portray healthy self-belief, but is really a cover for a deeply damaged self-esteem.