I have slavishly copied the "if filly then rating += 3", but "2 pounds slows a horse down by 1 length at the finish". I assume that +3 is from 9.00 - 8.11 is 3lbs, would that not equate to rating += 1.5? Mind you, I have no idea what "units" the rating is supposed to be, and uh, duh, it is rating_diff*0.5, I now see. Still though, what would you say the "units" of rating are? --Pete Lomax (talk) 02:12, 15 August 2021 (UTC)
- Although other systems are possible, as far as the Wren solution is concerned, the ratings are expressed in units of a pound relative to a norm of 100 which represents horse A's performance in Race 1. So, if a horse were rated 98, it would be expected to finish one length or 0.2 seconds behind A in a race in similar conditions where both horses carried the same weight.
- This in fact is how official ratings are expressed though they have a scale where, in flat racing, the best horses are rated at 120+ (sometimes 130+ for exceptional horses) and the worst horses at less than 40.
- In otherwise 'level-weight' races, fillies are normally given an allowance (often 3 pounds in flat races) to equalize their chances of competing with the colts though, as some of the best horses in recent years have been fillies (or 'mares' as they called when reaching age 5), one wonders whether this is really necessary.
- In general the subject of assessing the merit of racehorses is a very complicated one with commonsense and judgement playing a large part as well as the basic science.