bigs Posted January 28, 2008 Share Posted January 28, 2008 Ok, I've been trying something the last few weeks regarding horse race system and I've reached some conclusions I hope:drums So I'll explain how the selections are made: 1 - if a race has 'n' runners, the price must be AT LEAST (n-1)/1 (e.g. 11 runners, the minimum price is 10/1). 2 - horse must have at LEAST 1 win in the last 6 starts. 3 - horse must have won AT LEAST 1 time over going. 4 - jockey must have at least showed 1 time over course and 1 time over similar distance. 5 - either STABLE OR JOCKEY must have positive return on 1 unit stakes over all races at the track (this one is to be seen yet) 6 - stake to bet will be decided according to Slapdash's kelly criterion thread as follows: Let m be the profit you'd make on a 0.5 unit EW bet if the horse wins, and let n be the profit you'd make if it places (so, for example, if the odds are 10/1 and a place pays 1/5 the odds, then m = 6 and n = 0.5). Let p be the probability of the horse winning, and let q be the probability of it placing (but not winning). So 1-p-q is the probability that it is unplaced. Now let: A = mn B = (p+q)mn +pn +qm -m -n C = pm +qn -1 + p + q. Note that C is just your expected profit on a 0.5 unit EW bet. Then the optimal proportion of your bank to use as the unit stake (so the total stake is twice this) is [b + sqrt(B^2 + 4AC)]/4A sqrt means square root. If any of you people wants to contribute with advices :) you're more than welcome Quote Link to comment Share on other sites More sharing options...
bigs Posted January 28, 2008 Author Share Posted January 28, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" Just to add, as I'll be doing this the previous night, I'll use the SP BETTTING FORECAST Quote Link to comment Share on other sites More sharing options...
bigs Posted January 28, 2008 Author Share Posted January 28, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" All E/W STAKES are in units assuming 100 bank. (thank God for matlab for helping in the stakes :)) AND it is considered HALF stake to win and HALF stake to E/W, so the stake is the TOTAL! Folk 250 Saraba @ 10/1 ( 4.12 Units ) 320 The teuchter @ 33/1 (1.1 Units) 420 Pauntley Gofa @ 8/1 (5.58 units) & Bally Rainey 20/1 (1.73 units) =================================== Southwell 200 Owned @ 12/1 (3.53 units) =================================== Taunton 140 Le Beau Bai @ 14/1 (2.67 units) 340 Lady Roania @ 20/1 (1.92 units) 410 Brave Vila @ 10/1 (4.13 units) (despite having other horses that fit the parameters) Quote Link to comment Share on other sites More sharing options...
slapdash Posted January 28, 2008 Share Posted January 28, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" The probabilies I'll use for P will be 1/(win odds) and for Q it will be 1/(place odds) e.g. if a bookmaker sets the win odds of a horse to win @ 10/1 the P would be 1/(10+1) = 9%, and for place if it would pay 1/5 of the win odds giving 10/5, or 2/1, Q = 1/(2+1) = 33.3% I'm not quite sure I understand what figures you're using. What are you using for what I called m and n? Also, my q was the probability of placing but not winning, so in your example, the bookie's odds give a probability of 33.3% of placing, but that includes the 9% probability of winning, so shouldn't Q be 33.3% - 9% =24.3%? Quote Link to comment Share on other sites More sharing options...
bigs Posted January 28, 2008 Author Share Posted January 28, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" You're right slapdash, place BUT NOT winning ;) I'll have to change the code then... my mistake! m and n are based on the odds of the bookmakers, calculated properly :) Quote Link to comment Share on other sites More sharing options...
bigs Posted January 29, 2008 Author Share Posted January 29, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" Actually, something is not quite alright, my final stake is always zero now... Gonna look through the mats once again! Quote Link to comment Share on other sites More sharing options...
slapdash Posted January 29, 2008 Share Posted January 29, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" You're right slapdash' date=' place BUT NOT winning ;) I'll have to change the code then... my mistake! m and n are based on the odds of the bookmakers, calculated properly :)[/quote'] If you're basing p and q and m and n on the odds of the bookmakers, then I think the formula's going to tell you to stake nothing, as you'll be using the same values for the "true odds" and the "available odds", so according to those figures you'll have no edge. But maybe I'm misunderstanding what you're doing. Quote Link to comment Share on other sites More sharing options...
bigs Posted January 29, 2008 Author Share Posted January 29, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" No, you are spot on, I figured now, after 5 minutes of going through it! I have somehow to manage to get the "true odds" Quote Link to comment Share on other sites More sharing options...
slapdash Posted January 29, 2008 Share Posted January 29, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" Well, at least it means my formula is probably right. :ok Quote Link to comment Share on other sites More sharing options...
bigs Posted January 29, 2008 Author Share Posted January 29, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" Yes it is :) well slapdash, it was bugging me those probabilities p and q ... and why I was calculating based on bookmakers price on offer... Felt weird, and after you called my attention to it, there was light :) Thanks for the input! :) Quote Link to comment Share on other sites More sharing options...
bigs Posted January 29, 2008 Author Share Posted January 29, 2008 Re: Following Slapdash's thread "Kelly criterion for E/W bets" System on hold until I figure a couple of things out! Quote Link to comment Share on other sites More sharing options...
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