UK Horse Racing's Class Differentials
This morning I was asked the following to clarify something and I think that this is best shared because it may help others grasp how things are reported.
In the class/ weights differentials you have written above "...class and weight is positive and trainer/jockey is negative"
Can you just clarify, do you mean
1. That the negative numbers (those with a minus before the number) are just that i.e that there is a drop in class and weight and therefore beneficial thus a positive for that particular horse
2. Do you mean that the positive number (those without the minus) are as they seem i.e a positive number and therefore beneficial to that horse.
The first thing to be aware of is that within UK Horse Racing all values are "Bigger Are Better". There is one exception and that's the Weight Delta figure which compares the horse's weight with the average weight carried in the race. Other than that, a positive number is better than a negative number and a large positive number is better than a smaller positive number.
So, when we compre two horses' Class Differentials; the one with +5 is better than the the one with -5. The +5 means that today's race class is five pounds better than the average race class run in, i.e. it's five pounds lower. The horse with -5 will find that today's race class is five pounds tougher than its average race class.
The same with the Weight Differential. If a horse has +10 then it will be carrying ten pounds less today (i.e. ten pounds to its advantage) compared to its average weight carried in the past. So a horse whose average weight carried is 10-00 and is carrying 10-05 today then it will be five pounds worse than its average therefore the Weight Differential will be -5.
The Class & Weight Differential is simply the sum of the Class Differential and the Weight Differential. So if a horse, ROCKING HORSE POO, has a Class & Weight Differential of, say, +15 then the combined Class and Weight for today is fifteen pounds better than its average in the past.
Again you will note that Bigger Is Better.
So back to your question. The first part which demands a positive Class & Weight means that the Class & Weight Differential has to be positive. In other words the combined class it faces today along with the weight carried today has to be lower than than it faced in the past, i.e. it has to be in a position of advantage as would Rocking Horse Poo has.
If we look at the ratings for the 2.20 Wolverhampton today (below) the top rated is Tamarin. The Class Differential is 6.1 but the Weight Differential is -6.6. This means that Tamarin is running in a lower class than usual but is carrying more weight than he has on average in the past. If we combine these two then the Class & Weight Differential is negative, i.e. -0.5 .
The next part of your question is the Trainer/Jockey being negative. The Trainer/Jockey combination is usually abbreviated to TJ and it simply looks at how profitable the combination of Trainer and Jockey have done. We look at the combination of the trainer and jockey at all courses and all race types. So, for this race at Wolverhampton the trainer and jockey have raced together 320 times, won 61 but have shown a loss of -11.63 if one were putting one point on each of their rides. Therefore the Trainer/Jockey value would be -11.63.
If we're only interested in the Trainer/Jockey combination here at Wolverhampton then that would be the TJC figure (Trainer/Jockey/Course). There's a whole pile of these combinations of Trainer, Jockey and Course so we can look in the ratings for TC (Trainer/Course) or JC (Jockey/Course). Again, Bigger is Better.
Back to your question.
Option 1 is wrong as a drop in class is beneficial but the figure would be positve and not negative.
Option 2 is correct as a positive number is beneficial.
Updated 4th June, 2015