The Stock Market has a good system of useable stats [the market index] because to become part of them certain peramiters are required to be met before a Company becomes listed [joins the Index]. If this was not the case the Index would be unreliable and useless.

There is no reason, especialy considering all the stats available here, why a similar "Index" could not be arrived at in horse racing.
To qualify [to be a meaningful unit]for the Index, races that contibute in a profitable way to it only, can join."Wanna-be's" like Maidens dont get a look in until they prove their mettle.Ditto to Fillies and Mare races:too unreliable because of the hormone thing.Hudles...the nag carring your money always falls over and 1000m races are a bit dodgy due to the start thing,which has our money beting on...the start thing.Heavy tracks,well how heavy is it? Slow tracks require consideration perhaps because some swear by them as a good earn.
The Racing Index created would then have a meaning without "weighing" by statisticly useless races.