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Outlander Firstly your humility is to be admired. None of us has the answer as this rating business is subjective apart from time which I guess is the absolute. I experimented with my Raw time figures but a raw time figure doesn't tell you anything more than how fast the race was run, which in itself lacks that very important factor : class. I have gone back to my time and ability ratings and they are now showing positive returns.
As I said, I rarely bet in handicaps as finding one "well in" doesn't happen all that often as the Official Handicapper who I have the greatest respect for, don't usually make many mistakes. Its difficult for them to assess whether a horse has run to its ability or waiting for another day. This doesn't happen too much in non handicap races but might do if a trainer is looking for a lowly mark. They run it over the wrong trip, unsuitable going etc. Did I say Sir Mark Prescott? Well, you know what I mean. Handicap genius?
By confining my betting to mainly non handicaps the weight ranges are negligible and the race is usually won by the horse with the best ability. If I can tie in an ability rating with a time figure it gives me a good basis from which to start.
So. As you quite rightly say, Weight is a factor, but I look at it like this. If a horse is rated say 80, it will be assessed by the official handicapper as an 80 rated horse no matter what race it competes in. Its weight will be allocated by the conditions of the race. Higher class, lower weight and vice versa. In a handicap , when its mark is re-assesed it will be re handicapped from that figure of 80 and NOT the weight it was carrying. The weights may have been raised overnight by 7lbs but the horse is still an 80 rated horse. If it won well by say 2 lengths in a 6f race it might be raised say 6 or 7 lbs. so its new rating would be 86. But if it carried 9:10 it's rating wouldn't be 96 , which is what speed handicappers have to do when using weight in their ratings as they are usually working to a base of a horse rated 100 carrying 9stone. The official handicapper will then rate the rest of the field behind the winner with weight adjustments from the winners new rating and subjective opinion from the handicapper. I am sure you are aware of this but it leads me on to my reasoning behind my ratings.
I know Time handicappers who are way more experienced than me say that speed figures and official figures are not comparable as obviously speed figures are based on time. But then if thats the case why do they use say 3.5lbs per length for 5 furlongs, 3lbs for 6f etc. They should be calculating their ratings on lengths per second and weight shouldn't have anything to do with it. Admittedly there needs to be some adjustment on the lengths per second as a horse can't run 5 f speed for 8f. But there are many ways of calculating this. Some Speed handicappers adjust everything to 8f and some to 5f which I believe Timeform do.
Now, if you rate a race purely on time it is misleading, as I have found out to my cost, as this 80 rated horse may well run within a few fifths of a second to standard, in a very poor race, but its final time doesn't reflect the Class of the race. So do you take that at face value? I did for years without success. Class is of course extremely important. So I always wanted to be able to calculate a rating that was comparable to the OR if I could. I could then look at my figures and see if a horse was improving or running to its Official Rating
A few years ago I read an article somewhere by a previous employee of Timeform who stated that pure time figures by themselves were really of limited use and it was very important and essential to have an ability/form rating which would reflect "class". (Hence Time-Form)
I could have subscribed to Timeform, but where's the fun in that !
So I set about trying to come up with something of my own that would give me this combination. It is a very simple formula and no doubt the purists will think it doesn't make sense but it works for me. My base rating is not 100 but an ability rating I use based on "form" and "class". This is not the Official Rating . My speed rating is based purely on lengths per second with adjustments for different distances , GA, and deducted or added to my ability rating depending if the time the horse ran either was fast or slow. The figure for the winner is put into My Ratings page and calculated automatically although I change the lbs per length to coincide with the official scale. I do not make any adjustment for weight from the winner once I have my rating. It is what it is, whether it carried 9 stone or 10 stone. I understand that there will be a lot of disagreement suggesting it is illogical and doesn't make sense and has to be weight adjusted but I am only doing what the Official Handicapper does. Initialy. The rest of the field are rated with weight adjustment from the winners RATING and weight carried. There will be little weight adjustment as the races are all non handicaps.
I also only rate up to 8f and do not bother with NH. To me any race over 8f is more about stamina and ability rather than "time". I don't get involved with NH for various reasons, and of course you are going to get fast times at big meetings like Cheltenham but egg and spoon races at somewhere like Market Rasen are a waste of time for Speed rating assessment, but thats only my opinion and I am sure there are many speed handicappers who love NH.
I am pretty confident now that if I rate a horse to be 75 it won't be too far away from the OR. If the OR for that same horse is 69. it will be certainly worth looking at for betting purposes. I have a pure speed figure adjusted for distance plus a good ability rating. I hope you enjoy the read but of course this is only my way of rating a race. There are countless others, many better and lots worse.