However rating individual past performances is a different matter. By doing this you can see under what circumstances the horse rated particularly well or badly, and then compare those circumstances to todays conditions to make your assessment of its chances.

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- Are the ratings their best rating or a last time out rating. Eg a horse may be rated 80 on its debut run but on its four runs since it has run to 36, 38, 35, 31. I would be highly doubtful it will run to 80 again so its rating isn’t really helpful.<br>
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- Is/ are the horses progressive or exposed. If the horses are all exposed and fairly consistent then the ratings are clearly very useful and the "value" is easy to spot. If the horses are progreesive you are guessing a little on how much improvement there is and the scope for improvement has to be factored in to the price, eg a horse rated 85 after 10 runs is 2/1, a horse rated 80 after 1 run is 10/1, I’d prefer to be on the latter.<br>
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- Are conditions ideal? Has its best rating come over the distance and going or is it a soft ground specialist? Horses running under unsuitable conditions can usually be ruled out, or the price must be very big to arouse interest. And finally, is the horse stepping up in trip. Eg a Galileo- Imagine colt stepping up to 12f from 8f could really leave his old rating behind.<br>

<br>So imo ratings are a tool that can seek value and even make your selection for you, but particulary with 2yos a little caution is needed as sometimes they are rendered irrelevant. I’ll get shot down EC but that’s my personal experience.;)

]]>Yeah, you have to take into consideration today’s conditions.

(possible exception is with unexposed horses who haven’t had time to show their preferences – but even that is questionable)

*Can an accurate forecast be made from ratings…and is there any point? *

I read an article in Smartsig a couple of year’s ago which suggested a method of calculating probabilities from ratings using standard deviations.

It was interesting stuff though I seem to remember the calculation involved in even just a 10 horse race was pretty damn complicated.

Steve

]]>Steve – I’d be interested in looking at that Smartsig article if you still have it. I laboured long and hard to find a way of converting ratings to prices and eventually managed it using a constant in a formula. It took me ages and ages to discover my missing link (the constant) and it was a real eureka moment when I blundered upon the idea of using one. The basis for my theory is to assume that each horse will run to a certain level (it’s rating) plus or minus a certain constant. Once you know all the possible finishing positions (assuming each horse will have a finite number of possible finishing positions derived from it’s rating) it’s relatively easy then to establish a probability for each horses chance of winning (based on it’s rating relative to the others).<br>An inexact science but a useful tool nevertheless.

]]>Sorry about the decimals.

Based on your ratings and the current RP forecast I’d be looking closely at the two Easterby runners (Aitutaki and Seaton Snooks) and also at both Cedarlea and By the Edge. On a statistical note the horse mathematically representing the best value based on your ratings and the RP forecast is By The Edge.

I note however that certain of these ratings are for horses who haven’t run so i guess this is all hypothetical!

]]>Then again, given that anyone’s ratings are subjective, I suppose you would have to weigh up whether the extra time turning ratings into ‘accurate’ prices would be time well spent. I think there may be a danger in that expressing opinions numerically gives a false impression of statistical objectivity, when even the best ratings are no more than opinions. Is an opinion really expressable to two decimal places? Are we in wheels on a tomato territory here? If your ratings are good and you are satisfied they take into account all possibilities, a rough ranking of horses might well be enough to spot the clear value.

Ultimately though, only practice will tell. Maybe running the two approaches together over a period of time will give you some indication of which is the most effective. Perhaps other forumites who create ratings might like to do the same.

Without wishing to divert this into a ratings-compiling thread, or God forbid, a debate on the merits of ‘value’, I have found one of the problems with a ratings approach is that too little emphasis is given to the way the race might pan out. I am (very slowly) trying to devise a way of working out rough probability from trying to predict how the race will develop, what is the liklihood that each horse will take the early lead, for example. Others are much more advanced in their study of this and this is probably where sectional times come in. To be fair, EC has already alluded to the fact that such considerations are already built into his ratings to a certain extent.

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