What does A/E mean in Horse Racing and Betting
The A/E statistic in horse racing is also known as the Actual vs. Expected ratio. It is commonly used to measure the profitability of betting selections.
This statistic helps bettors and analysts work out how well a particular set of criteria or factors predicts the actual outcomes of horse races.
The formula for A/E is quite straightforward. As it equals Actual Winners divided by Expected Value.
Here's a breakdown of the components:
Actual Winners:
The number of times the selected set of horses have won their races. Simple.
Expected Value:
The number of winners you would statistically expect based on the chosen criteria. Not so simple, see below.
When the A/E number greater than 1, it suggests that the selected criteria are performing better than expected. Indicating potential value in those selections.
Conversely, an A/E number below 1 implies that the selections are underperforming compared to what would be expected statistically.
How to work out the expected winners value.
So the actual winners equals the number of winners your system or idea has actually found.
For the expected value we use the odds of all runners that your system has found, we then turn these odds into a percentage EG 100 divided by the decimal odds.
So for example the Betfair SP of a horse was 5.0 then 100/5.0 = 20. The horse had a 20% chance of winning according to the odds.
If you're using fractional odds you convert to decimal first by converting the odds to a base of 1 and adding the two halves. EG 5/2 is actually 2.5/1 add 2.5 to 1 and get decimal odds of 3.5.
100/3.5 is 28.57 and that's the percentage chance of a 5/2 shot.
Once you have all of the odds you can work out the percentage chance of each runner and total this up to get the expected value.
So let's work an example…
In teh real world you would be dealing with 100's of results maybe 1,000's but to keep things simple we'll go with 5.
Won 6/4, Lost 3/1, Won 4/1, Lost 5/1, Lost 6/1.
Converting those to decimal odds we get.
Won 2.5, Lost 4.0, Won 5.0, Lost 6.0, Lost 7.0.
Let us say we have a set of results that produce the following 5 results.
As a percentge chance they are 40%, 25%, 20%, 16.7% and 14.3%
Total those and you get 116%.
We divide that by 100 and we get 1.16.
So our calculation is 2 winners divided by 1.16 = 1.72
If you ever get 1.72 in the real world with a big sample it's time to celebrate, of course this is just a made up example, anything over one is worth further investigation.
