Do you know, I’ve
never, ever
heard anyone argue in
mathematical
terms about his methods, it’s always a ‘wotta load of sh*t’ followed by half-a-dozen ‘smileys’. Utterly ridiculous and very redolent of our times.
You win.
Mike
You hear Ginge constantly debate his methods Mathematically Mike,You hear me tell him you cant use Maths in Horse racing because Horse Racing has nothing to do with Maths.
If only bookmakers felt the same way you do Gord, the game would be so much easier! 
If only they’d offer 3/1 about all four horses in every 4 horse race, 5/1 for 6 horse races etc. Don’t you know how bookmakers work by now?
Bookmakers use maths to figure out what their first offer will be (when the market is first formed or ante post directly after a horse has run). Afterwards market forces move the prices.
Say there’s a four horse race, the bookmaker’s odds compiler studies the race and believes:
B) Has 3/4 the chance of (A).
C) Has 1/2 the chance of (A) and 2/3 the chance of (B).
D) Has 1/4 the chance of (A), 1/2 the chance of (C) and 1/3 the chance of (B).
The only way that works out in to a 100% book is:
A) 40%, B) 30%, C) 20%, D) 10%
With level stakes punters need a strike rate of 40% @ 6/4, therefore 6/4 = 40%. 30% 9/4 (well almost, 9/4 = 30.8%), 20% 4/1 and 10% 9/1. Therefore (in a competitive market) he adds a mark up to those figures and offers:
A) 11/8 (42.1%)
B) 85/40 (32%)
C) 7/2 (22.2%)
D) 15/2 (11.7%)
Working to a 108% book.
At level stakes a punter needs a 42.1% strike rate @ 11/8, 32% @ 85/40, 22.2% @ 7/2 and 11.7% @ 15/2.
If it is possible for an odds compiler come to an opinion about the chance of a horse, then it is possible for us as punters to come to an opinion (whether we do so by making a 100% book or not). He/she does not need to know what percentage chance each horse has of winning the race, just have an opinion that horse (A) has either
more
or
less
than a 42% chance of winning etc.
So if the punter does NOT believe (A) has a better than 42% chance of winning there is ABSOLUTELY NO POINT in backing the horse @ 11/8.
Nor should he/she back (B) @ 85/40 if not considered more than a 32% chance, or (C) @ 7/2 if considered less than 22%.
But even if the punter believes (D) to have the worst chance of winning of the four candidates, he should back (D) @ 15/2
if
he believes the horse has a better than 11.7% + margin of error, say 13%+ chance of winning. Because a 13% strike rate @ 15/2 shows a profit. (Some punters may want a bigger margin for error).
Obviously, a punter needs both a good understanding of form/racing and be able to evaluate that form in to chance of winning. So he/she can identify horses at bigger prices than they should be. There will always be some who will know everything about form/racing, and can talk the hind legs off a thoroughbred – yet are incapable of evaluating it in to chances and so profit.