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A Detailed Look at Chester Draw Bias
A Detailed look at Chester draw bias (5 furlongs) 2005 to 2008
by David Renham
Chester is considered one of the most biased in terms of the draw in this country. The configuration of the track (horses running round a tight left-handed bend) suggests that any bias is likely to remain constant over a long period of time. I have looked in detail before at Chester draw bias, but the stats remain so strong I feel it is worth keeping up to date with the current state of “play”.
I have chosen the period from 2005 to 2008 to study the last 4 full years. As with all my draw research, I have only considered races with 10 runners or more and have split the runners into “thirds”. Hence in a 12-runner race, draws 1 to 4 would lie in the bottom “third”, draws 5 to 8 in the middle “third”, and draws 9 to 12 in the top “third”. 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 have chosen the minimum distance of 5 furlongs where the draw bias is traditionally at its strongest. There have been 31 qualifying races over 5 furlongs during this period with the draw split as follows:
As the figures indicate, there is a very strong bias to horses drawn low. In turn, horses from the middle "third" of the draw have a clear advantage over horses drawn high. Horses drawn high have a dreadful record winning on average around 1 race in 10. (On a non-biased course this would be nearer 1 win in 3). The clear conclusion therefore, is the further away from the favoured inside rail the horse is drawn, the harder it is to win.
Now the bias to low drawn numbers should come as a surprise, but essentially the bottom third of the draw are seven times more likely to win than the top third of the draw.
My next point of research looks at handicaps only. Handicaps should provide the best data as these are races where all runners are supposedly handicapped to finish in a straight line. There have been 24 handicaps with 10 or more runners during this four-year period:
These are very similar results to the overall ones. It seems if anything the bias is slightly stronger with the bottom third of the draw posting 8 times as many wins as the top third of the draw.
In order to give a more detailed picture of the draw bias at Chester, I have decided to look at a variety of different “angles”.
The effect of field size
The maximum field size over 5 furlongs at Chester is 16. I have split the races into the following field size groups. Firstly, races with 10 to 12 runners, and secondly races with 13 to 16 runners.
Races with 10 to 12 runners
There were 19 qualifying races over the 4 years studied. Here are the statistics:
Although the bottom third of the draw still provided over 60% of the winners, it is clear looking at both the win stats for the top third of the draw, and the placed stats for all portions of the draw, the bias is slightly less strong with this size of field. It should come as no surprise and is what I would expect (hope for).
Races with 13 to 16 runners
There were only 12 qualifying races with “big” fields:
In races of 13 to 16 runners, horses drawn in the top “third” of the draw have provided 0 winners and only 3 placed horses. These 3 runners came from a total of 55 horses that were drawn in the top “third”!! The reason higher drawn horses struggle in bigger fields is fairly obvious – the wider the draw of the horse, the further away it is from the favoured inside rail.
The effect of the going
Good to firm or firmer
There have been 18 races on good to firm ground or firmer over the past 4 years. Here are the percentage splits:
Amazing to see that 16 of the 18 races were won by horses drawn in the bottom “third”!
Good or softer
There have been 13 races on good or softer ground with the following results:
The bias seems far less strong under these going conditions although the sample of 13 races is rather too small to making sweeping statements from. However, looking at the going statistics overall, they seem to indicate that the advantage to lower drawn horses strengthens as the ground gets firmer.
Individual draw positions
All the research to this juncture, points to the fact that the lower the draw, the better, at Chester over the two sprint trips. Let us look at individual draw positions to see this more clearly. Here are the stats:
Draw 1 has had an amazing record winning over a third of all races. Indeed draws 1 to 6 provided 28 of the 31 winners (90.3%). There have been 0 wins for horses drawn 11 or higher.
Profitable betting angles
Over the past four years there have been numerous profitable betting angles:
1. Backing the lowest drawn stall “blind” (usually draw 1, but would be draw 2 if draw 1 was a non runner) would have produced a level stakes profit of £498.30 to £10 level stakes at SP. That equates to a return on investment of 160.7%!!
2. Backing the second lowest drawn stall “blind” would have produced a level stakes profit of £105.00 to £10 level stakes at SP.
3. Laying all runners drawn 11 or higher would have produced 57 winning lays and 0 no losing ones. Hence laying at £10 level stakes per selection would have produced a profit of £541.50 after taking the 5% commission into account.
4. Perming the three lowest draws in full cover tricasts (6 x £1 perms) would have produced a small profit of £23.14.
Other stats for 5f races at Chester (10+ runners)
1. The top three in the betting provided 17 of the 31 winners (54.8%).
2. 11 of the 31 winners made all the running.
3. Just 1 win in 36 for horses off the track for more than 8 weeks.
4. Horses priced 22/1 or bigger have provided 0 winners from 94.
5. Last time winners have a poor record with just 5 wins from 54 for a loss of £300.50 (to £10 level stakes).
Finally, here is a simple system that would have provided good profits over the past 4 seasons:
1. Drawn 1 or 2
2. Ran within the past 8 weeks
3. Age 2 or 3
The results would have been thus:
Strike rate 43.5%
Profit (to £10 level stakes) +£673.30
Before I finish, a big thanks to Simon Walton at Proform racing whose database helped me to produce some of the stats for this article.
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