I am hoping someone with some mathematical probability knowledge will be able to help me here. I am looking at a possible favourites lay system but I need to know if the testing results I have are at least a semi-accurate indication of of the future. The system I am looking at considered 1000 races over the past 4 months and selected 70 races to lay the favourite, if I were to randomly select 70 races in a group of 1000 what would be a probable win percentage of favourites in those 70 races?

Cheers,

Matt.

I'm no rocket scientist (or mathmatese) but wouldn't it still be the long term favourite winning percentage of around 30% - especially in the long term?

__________________
Never give up on a dream just because of the time it will take to accomplish it. The time will pass anyway.”

― Earl Nightingale

Its not Rocket Science OCHO.
You are correct with 30%

Sometimes people try to make simple things complicated.
Like the Origin of the Universe.
Something made it.
Lets call it GOD.
Too easy.
The Rocket people can have their Big Bangs and there Primordal Soup.
I got a Life that needs Living.

70 is too small a sample size ans saying 30% is too simplified. what if I chose 70 races where the favourite was $1.50 or less. I would expect at least 50% strike rate not 30%. What if I chose 70 races randomly but they all had favs at $4+ prices. In that case the strike rate should be 25% or less.

The better option is to determine how many winners you should have got from those races. Its simple enough to work out . 1/odds = chance of winning. Add up all of the favs using this formula and it tells you how many winners in those 70 races were expected. This doesn't account for commissions so you should adjust for those too if you using tab prices. For betfair you don't have to worry as commission comes out after the winning bet so the odds on display are generally to 100%.

And when you take all those various 70 races into consideration, I'm betting (in the long term) it will come out at around 30%. You haven't seen the thread about the wisdom of crowds then, UB?

__________________
Never give up on a dream just because of the time it will take to accomplish it. The time will pass anyway.”

― Earl Nightingale

Hey Mattio.

Probably looking for a quicker answer than this but if it was me id look at it like this.

Id work out the strike rate of your favorite in those 1000 races then wait till your 70 selections grows to 1000 and see if it stacks up.

Worse or the same throw it out, significantly better youre onto something.

Some people you can rub their noses in it and they still won't see or smell it.
Its why we have Winning Punters and Losing Punters.

The ONLY reason a Punter Loses is because he is doing something wrong.
And until they realize and understand what it is , and make it good , then they will continue to fail.

UB the total odds of all those was 264.60 (NSWTAB) so is the formula (1/264.60)*117% to account for the TAB takeout?

Results for 10 groups of randomly selected races (70 consecutive races)
Losers
51 0.729 0.271
44 0.629 0.371
48 0.686 0.314
50 0.714 0.286
42 0.600 0.400
53 0.757 0.243
49 0.700 0.300
47 0.671 0.329
49 0.700 0.300
43 0.614 0.386
0.68 0.32
In the groups selected the longest expected Losing run for the fav worked out to be 15, but 1 group had 16 consecutive losing favs.

Hi woof43,

Thanks for that, would you mind explaining what the groups of numbers mean please? I am guessing the last number in the row is the win percentage but I am not sure about the others.

Cheers,

Matt.