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General Category => Ask the Experts => Topic started by: Catalin on June 20, 2002, 06:23:33 PM

Title: Probabilities and Value
Post by: Catalin on June 20, 2002, 06:23:33 PM
Much has been made on both boards lately about probabilities (i.e. "true odds") and value based betting.  A prime example was Saturday's 9th at Churchill where Spain was bet down to 2-1 second favoritism.  Having seen both TG and Ragozin for Saturday's Churchill card,  I have no problem going on record that Spain's true chances of winning were far short of the 1 in 3 being offered.  If memory serves she was no better than co-second or third fastest going in, was giving weight to the two ML favorites, and had drawn a post that guaranteed at least a length of ground loss.  Despite a pretty good pattern on both sheets, she looked at least to me no better than 3rd most likely to win.  I believe I recall Mall stating that he pegged her at upwards of 9-2.  Soupy, he of specious reasoning makes the argument that the 2-1 looked pretty good when she won.  EVERY winner looks like a good bet AFTER they cross the line.  Unfortunately most of us are unable to get a bet down once they break the tape.  The fact of the matter is that if we ignore true odds, the law of large numbers will quickly whittle away our bankroll, no matter how good we think we are at picking winners.

Consider the following example.  Suppose I were to tell you ahead of time that the coin I was flipping was weighted such that it came up heads 70% of the time, and tails only 30% of the time.  Now suppose I established a book on the outcome and offered the following odds:

Heads      1-5
Tails      9-2

What's your wager?  Is it the favorite (Heads) who looks far more likely on paper than Tails, or is it the 9-2 second choice?  Anyone choosing heads is doomed for long run failure.  As n approaches infinity where n is the number of trials, coin flips, races, etc., you would wager

$1 on Heads and receive 1-5 or (1.2) * .7 (probability of heads) or only 84 cents for every $1 wagered.  

On the other hand while Tails wins far less frequently, the bettor would expect to receive a payout of 5.5*.3 or $1.65 for every $1 wagered.   So now who do you like?  This is may be a pretty simplistic example, but the concept isn't any different from the Saturday's 9th from CD re Spain.  

Betting horses that pay below their true probabilities will ALWAYS result in a long run loss.  That's why success is predicated on your ability to accurately estimate true probabilities.  Those who bet selections rather than PRICES have NO SHOT whether you're betting the horses, wagering on a coin flip, or playing the biggest crapshoot of all, the stock market.
Title: Re: Spain + 'true odds'
Post by: Godzooky on June 21, 2002, 04:43:36 AM
I think it\'s funny that you confuse \'true odds\' with \'your odds\'.

The coin flip actually has \'true odds\', while your judgement is apparently so infallible and all seeing that your own odds become reality in judging a race.
Do you know what \'hubris\' means?

To begin with, Spain was 3.7-1 ---- almost double the odds you cited.
Already, there\'s a knock on your judgement.
Secondly, the even money favorite was a stretch and should have been 6 or 8-1, that alone should give you a hint about Spain\'s \'true odds\'.
The fact is, she was much the best, should have been favored, and you simply failed in handicapping the race.

Mall was convinced that no mare in foal could win a stakes, and apparently he was also dead wrong.
I guess Lukas won\'t be calling him for advice, after all.

Personally, I don\'t look for reasons to bet short priced horses, whether they\'re value or not.
Some people would jump on a 7/2 that should\'ve been 2-1, but that\'s just not me.
The quality of the horse is obvious --- the quality of your judgement is not.

By the way, if she was \'third best\' (according to you), who were the 2 horses more likely to win, and why?
Title: Value Handicapping
Post by: Mall on June 24, 2002, 11:13:39 AM
Let me humbly suggest that you\'re missing Catalin\'s very important point. Assume, for sake of argument, that Catalin, Robes(Spain did not represent any value) & I were all wrong about Spain\'s actual chance of winning the race. That would only mean that we were wrong about a particular race & perhaps need to improve our handicapping. That wouldn\'t change the fact that the overall approach Catalin is suggesting is the one & only way to achieve a long term positive roi. Every study & every serious treatise says essentially the same thing, namely that an above average value handicapper will do better than an excellent selection handicapper over any extended period. IMHO, it is hubris for anyone to suggest or believe that he or she is the one handicapper for whom the laws of mathematics do not apply.

BTW, I did not mean to suggest that I was of the opinion that a horse running in foal has no chance to win a race, although I have yet to meet a horsemen who viewed it as a positive. My pt was that someone who was holding himself out as an expert did not know this very basic & very public bit of info.
Title: Re: Value Handicapping
Post by: Alydar in California on June 24, 2002, 07:04:16 PM
Mall: I thought Catalin\'s (and your) posts were excellent, and as a practical matter, I agree with you and him. But it is impossible to win an argument on this subject. Let me ask you this: If you could know everything there was to know about an upcoming race, what would your odds line look like? It wouldn\'t be necessary to have one, would it? I believe the problem is with the term \"true odds.\" When we make a \"true odds\" line, aren\'t we really making an odds line on our own ignorance and fallibility? After all, one horse will win the race, and if we knew everything about an upcoming race, we would be able to identify this winner.
Title: Re: Value Handicapping
Post by: Mall on June 24, 2002, 07:26:31 PM
\"True Odds\" might not be a technically accurate way to describe a particular dopester\'s judgment on each horse\'s percentage chance to win a particular race, although I\'d like to think that my odds line is based on something more than ignorance. The fact that all of us are fallible, not to mention the randomness of racing itself, is in my view the strongest argument in favor of developing one\'s skill at making such judgments & only betting when the public\'s view is different enough to create a large enough edge, i.e. overlay, to make up for the inevitable mistakes & unpredictable results. To answer your question, if there was some way that I knew in advance to an absolute certainty that a particular horse was going to win a specific race, I would take whatever odds are offered. Now I have a question. Isn\'t it about time for you to venture out of Calif & test your wits against the best of the best at Sar? That free beer from Phil is going to go down awfully easy after the card.
Title: Re: Value Handicapping
Post by: Alydar in California on June 24, 2002, 08:01:59 PM
Mall: Unfortunately, there seems to be no disagreement here. Making an odds line is a modest act. (It is an admission that there are countless things we don\'t know.) Calling it a \"true odds line\" is not. The reason it\'s impossible to win an argument on this subject is that someone can always reply that he knew more about this particular race than you or I did. In other words, he can claim that he was closer to the 100 percent certainty available to someone who knew everything (including who would toss the rider) about an upcoming race.
In this case, \"ignorance\" means not knowing who would break slowly, who would get DQed, etc. We are all ignorant.

As for your question, I have a 12yo basset hound who cries whenever I leave the room. I hope to be stuck in CA for a while, but I would love to meet you at Saratoga eventually. Del Mar ain\'t even close.
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