positive expectation win bets. c div p er 1) 2) By the Harville formula (Harville ), the estimated probability of a 1,2 or. simple win betting ratios and the Harville formula). These indirect estimates would then be paired with the direct estimates (the betting ratios in the exacta pools). HARVILLE, D. A., “Assigning Probabilities to the Outcomes of Multi-Entry Competitions,” J. Amer. Statist. Assoc., Vol. 68 (), pp. HAUSCH, D. B.
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Horse Racing Forum – PaceAdvantage. Is anybody able to tell me these formulas or point me somewhere I can get them?
Basically, you have probabilities for each horse jarville. The probability of BA would be 0. SInce there are horses who have a good prob. Thanks for the reply. Isn’t that the normal Harville formula though, I understood that the discounted Harville was a modification of this to help counter the problem that as you say a horse may have no chance of winningbut high of placing or high chance of winning and harviloe for placing. I believe Banacek is right.
I recall reading the article written by Mr. Harville at the Georgetown U. Library many years ago. Harville described his use of his formulas for place and show wagering at an Ohio track and found his results to be “mediocre. I hadn’t heard of a variation, but you certainly could adapt them to fit a particular race. Many races might be formlua that the Harville formulae would work fine, but other races would need an adaption to the numbers that would be very specific to the horses in that particular race.
Thanks for the replies, I have also been trying to get my head around the Henery formula, does anyone know this? Also the Shin probability formula for adjusting for fav-longshto bias. So am I right in understanding that if you are using your own probabilities then use the. I am a little confused I admit. Where have we got the ‘sum of probbilities’ from are you talking about the place probs now or the win probs?
I have the original henery formula which is very complex as I am sure you know but hadn’t beena ble to get the revised one, so thank you very much. Their ‘Discounted Harville’ approach is relatively straightforward and can be adapted for use in Excel, for example. Mwilding, If you have a database with public probabilities, you could have different coefficients than.
My coefficients for place and show in my model are different than the.
This is all based on individual win probabilities as the starting point. As later posters have indicated, the harfille correction figures are averaged over a number of races for a particular set of racing. So the corrections, for what they are worth, will vary. This subject theory is very academic, rather than practical or true to life – as is typical of economists – it is better to assess each race as it comes and just be guided by the average corrections – which you may judge too high or low for a particular race.
Things happen due to a cause – you need to forecast that cause – not apply a formula that only looks at effects.
Placing probability depends far more on the horses involved in a race than on the maths. Correcting this way is also a sweeping assumption and is not based on any evidence – just unproven economist theory.
harville – File Exchange – MATLAB Central
Michael, The “Discounted Harville” formulae, as requested Excel-like syntax – check accuracy: In a seven horse H1, H2, H3, The authors provide a table of intermediate values for both lambda and rho but, personally, I have found that the Henery values are satisfactory. This is not an exact science and, as such, an over-emphasis on precision is not warranted. A consistent, satisficing approach is sufficient.
Note that tractability issues arise because you have to sum over all exactas where H2 places in order to calculate the H2 place probability. Similarly, you have to sum over all trifectas where H3 shows to calculate the H3 show probability! Okay this is how I understand the formulas below, can anybody correct me if I am wrong. Michael, Apologies for not replying sooner but I have not logged on to the forum for a couple of days.
I inadvertently added an additional SUM term to both equations in my original repy – apologies – never post mathematical equations to forum late at night! Hi John, Thank you very much. Just had time to go through the top place equation.
I am getting a different result to you though when i do it manually and I can’t work out why.
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This bit works fine: What I am doing is 0. Michael, Did you remember to change the prob Forjula, wins value from 0. Hi John, Yes I definately changed that because I used your equation and then I formuula did each stage in excel seperately. For some reason that I still don’t understand, when I do it seperately I get the figure differently to you and it changes at the point above. I can’t see harvilld reason for this though!! Michael, As you say, it does not make any sense.
I suggest you leave it for 24 hours and perhaps a fresh look at that stage might lead to a resolution. Sorry for bumping a very old thread to the top as my first post on the forum.
I’ve been so impressed with the level of hsrville here, I’ve no idea how Hafville hadn’t found this forum before.
I’m not sure if jfdinneen or mwilding are still about, or if anyone else can help, but I decided to try in excel the formulas jfd contributed so generously below. The exacta formula works a treat, but somehow I cannot get a sensible result out of the trifecta formula.
Should the results of this add up to 1?
I suspect I have made a silly error somewhere, but any help would be greatly appreciated. Looking forward to reading and contributing more here, some of the old threads hold a lot of value. Please check for errors.
John Although I did not find the spreadsheet that JF Dinneen mentioned, I am much more interested in that blog site itself. There is some pretty interesting stuff there. I just clicked one on of the links “how not to be wrong It appears that Google deleted the original “Harville” spreadsheet from the blog some time ago, without requesting my permission? I have included the “informed Factor” size into my bet size calculations.
I have included it fkrmula the last 35 races and it improves the results let’s see how long that last.