More Draw Bias Research 2009 by David Renham

With many race courses taking steps to eliminate draw bias through watering or rail movement, draw bias has generally become less of a “hot” topic over the past two or three seasons. However, there are still some courses where draw bias is still prevalent and importantly consistent. This article looks at some of the course and distances involvedfor course biases in uk horse racing

In terms of data for this article I am only including races containing 10 or more runners. I have always used the 10-runner cut off point in my draw research – my reasoning behind it is that for a bias to exist, there needs to be a reasonable amount of runners. I am also restricting the research to handicap races only as these races are designed to be the most competitive.

My main method for analysing each race is thus - I divide the draw into thirds - those drawn in the bottom third (low), those in the middle third, and those in the top third (high). On a completely fair course the winning percentages for each third should be around 33% and, while some courses hover around that figure, others clearly do not. I will use this “thirds” method once again as a starting point, but I will look in detail, where appropriate, at other statistical methods in order to help unravel the draw bias picture.

The data for this article is taken from the last four seasons – 2005 to 2008.

Thirsk 5f

When Nick Mordin wrote his ground breaking book 'Betting For a Living' at the beginning of the 1990s, draw bias was something that 99% of punters probably did not consider. However, the Thirsk draw bias was one of the biases mentioned in the book, and nearly 20 years later, it still exists. Here are the stats for 10+ runner handicaps for the 5f trip at Thirsk since 2005: