Should I Use Raw Ratings Or Impact Values?

Which are better raw ratings or impact values? For those of you who may not have heard of impact values I should explain. An impact value is a method of discovering what a ratings impact is on predicting the result of the race. An impact value of 1.00 is no better or worse than expected. An impact value of 2.00 would mean that horses with the rating that achieved this impact value win twice as often as we would expect.

I shall write a full article on how to calculate impact values on another day but this brief overview should be enough to allow me to carry on.

Raw ratings can reveal a lot about the performance of a race horse, player or team. A bit of analysis on a rating can tell you whether it is stable and the intricacies of how it works. Ultimately you have to do a certain amount of work to be able to understand them. This is where the impact value has its first major benefit. We can look at an impact value and know exactly what it means without any understanding of how the rating is calculate.

Let us take an example of a horse with a form rating that is 365. This means nothing to us as we don’t know how it was compiled or what the other runners have. If I told you that this rating had an impact value of 1.50 then it immediately means something. We now know that this horse will win 50% or 1.5 times more often than we expect it to.

How often do we expect it to win? Quite simply we expect it to win as often as its probability from the odds just before the off suggests. This does not mean that any horse with a rating that has an impact value of over 1.00 is giving you a value bet. It isn’t.  The rating is only taking into account one particular aspect of the horse’s performance whereas the odds are taking into account all aspects of the horse’s performance. What it does tell us though is that this horse has already got an advantage in one area and we have an idea of the amount of advantage it will have.

Another benefit of using impact values over raw ratings is that by definition they are all on the same scale. A 1.00 is what we expect the horse to get and anything less is worse and anything greater is better. This means that if our horse with a form rating of 365 and a speed rating of 70 has impact values for these ratings of 1.50 and 0.75 then we know that the form is strong but the speed rating is weak. Although you cannot simply multiply these two together due to a number of reasons (which needs its own article to explain), if the other two horses in the race have impact values that look like:

Horse A – Form 1.50 – Speed 0.75

Horse B – Form 1.20 – Speed 1.00

Horse C – Form 0.90 – Speed 1.35

We can see straight away just by looking that our horse is actually quite severely hampered with his speed rating without any need for statistics of any sort.

The value of the raw rating is in the name, the fact that it is raw. This value has been created from the raw information of the horse and if you understand the rating and its nuances then it is going to provide you with a lot more information than the impact value is. I shall use the above as an example where our horse has a form rating of 365. If this was a rating that I had created and spent a lot of time working with then I may be able to tell you that this is not just a figure based on the individual horses form but a figure that takes into account the other runners in the race. Suddenly now we understand why the impact value is high, we have already taken the other runners into account in this race. Through my work with this rating I can tell you that when a horse goes above 340 in the form rating it has to have a very significant opponent in order for it to be beaten. Of course this would change our view of the race that we had based on just the impact values. A first glance at the impact values would have led us to think that although Horse A was excellent on form his speed rating meant that he was going to be no better than the other runners. With the new information from the knowledge of the raw rating we know that not only is Horse A over the 340 threshold but significantly higher, whereas only Horse C has a better than 1.00 impact value for speed and none of the others are close in impact value to form. Rather than dismiss Horse A as being close to the other we would still see him as a very strong contender and a horse we may want to be placing our bets on.

So which one should we choose the impact value or the raw rating? You should use both. Both used in conjunction for form readers, when the initial rating is well understood, can have an incredibly large positive effect on the performance of your selections. If you are using a statistical method then you can also use both although most people I know stick to one or the other. As of yet I have not found a good reason for just sticking to one and until I do I shall continue to mix them up and make a profit from doing so!

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