Table Of Odds And Chances

[Gingertipster]

Been talking about this for too long now but will explain the principals again and include the actual table this time. A punter who knows the percentage of winners he / she must win at a certain price, has a far better chance of making a profit than one that does not. Every punter knows for every £1 bet at 4/1 wins £4 + the £1 stake back. A return of £5 for every £1 staked. So if a punter has 100 individual £1 bets all at 4/1. Total stake £100. If he wins 20 of those 100 bets he gets back £100 (20 x a £5 return = £100) breaking even. If he wins more than 20 he makes a profit. Less than 20 he makes a loss. Another way of saying 20 out of 100 is 20%. So 4/1 = a true chance of 20%. So a punter who believes a horse (or whatever) has a 20% chance of winning should only back it if he can get better than 4/1. If he can not get better than 4/1 then he should look elsewhere for a bet. Now with 4/1. Add the first figure (4) to the second figure (1) = 5 Then divide the second figure (1) by that resultant figure (5) = 0.20 Then x that figure (0.20) by 100 to find the percentage chance = 20%. 4/1 = 20% 7/2 = 7+2=9, 2 divided by 9 = 0.222... x 100 = 22.2 therefore 7/2 = 22.2%. Unfortunately if a bookie works out a 5 horse race believing each horse to have the same chance (20%) he will not offer 4/1. He adds his percentage profit and offers early prices of 7/2 about each runner, working to 111%. (If there is little competition with few bookmakers betting on the outcome he may get away with 100/30 all runners). If you agree with the bookie there is no bet. If however, you believe one has a better than 22% (7/2) then that is the bet. Every horse / outcome should have a price to take. If you believe: A) has a 35% (15/8) chance B) 25% (3/1) C) 20% (4/1) D) 13% (13/2) E) 7% (13/1) All 5 prices added = 100%. And the best prices available are: A 13/8, B 11/4, C 100/30, D 6/1 and E 16/1. Then the bet to have is E, despite kowing it has the worst chance of winning. Because if you win 7% of your bets at 16/1 you will show a profit. All of the others would show a loss. (The prices in brackets above are the prices to beat for each horse). If you want an inacuracy rate it may be best to work your "book" out to 95 or even 90%. This also cuts down on the number of bets. Here is the Table Of Odds And Chances. Evens 50% 21/20 48.8% 11/10 47.6% 6/5 45.5% 5/4 44.4% 11/8 42.1% 6/4 40% 13/8 38.1% 7/4 36.4% 15/8 34.8% 2/1 33.3% 85/40 32% 9/4 30.8% 5/2 28.6% 11/4 26.7% 3/1 25% 100/30 23.1% 7/2 22.2% 4/1 20% 9/2 18.2% 5/1 16.7% 6/1 14.3% 13/2 13.3% 7/1 12.5% 15/2 11.7% 8/1 11.1% 17/2 10.5% 9/1 10% 10/1 9.1% 11/1 8.3% 12/1 7.7% 13/1 7.1% 14/1 6.7% 15/1 6.2% 16/1 5.9% 18/1 5.3% 20/1 4.8% 22/1 4.3% 25/1 3.8% 28/1 3.4% 33/1 3% 40/1 2.4% 50/1 2% 66/1 1.5% 100/1 1% 150/1 0.67% 200/1 0.5% 250/1 0.4% 500/1 0.2% 1000/1 0.1% To calculate odds on chances subtract the odds equivalent odds against chance from 100. e.g. 1/3 = 100% - 25% (3/1) = 75%. So 1/3 = 75%. With exchange prices the commission should be taken into account. Any selection a punter believes has a 42% chance of winning should only be backed at BETTER than 11/8. 12.5% 7/1, 6% 16/1 and 3% 33/1. As I said every horse has its price. An 11/8 chance has a true value of 42.2%. Of course nobody can say if a price is definately value or not value (should it be a 42%, 40% or 25%) it is only their opinion. But anyone thinking it is impossible to work out percentages sould realise bookmakers (their odds compilers) do it all the time to calculate their early prices. If they can do it so can we by studying form. I have gone over old ground. Sorry if this seems obvious or patronising, I have tried to do it in a way everyone can understand. It is though something that lots of punters still do not understand, probably because the betting media do not explain or publicise it. Any questions please ask.

[Sgt.Sunshine]

Re: Table Of Odds And Chances Isn't this stating the obvious? What am I missing here?

[Datapunter]

Re: Table Of Odds And Chances Hmmmm, so if i have a bet at odds of 2.00 then i should get a strike rate of 1/2.00 = 0.5 = 50% to break even. If i have a strike rate of 50% then i should get odds of 1/0.50 = 2.00 in order to break even. Doesn't matter if it's 1 bet or the average of a series. Wether you actually are getting value from a price can only be determined by looking at the result of a long series of bets made with a consistent method. To say value is present ( or not ) on any single bet is simply not possible. Here's the problem :

So a punter who believes a horse (or whatever) has a 20% chance of winning should only back it if he can get better than 4/1.

How do you know the 20% is accurate ? Therefore how do you know there is value in the 4/1 price ? Allow me to answer that myself : you don't. The only way, if you are going to include "value" in the bet selection process, is to determine ranges based on historic results. Can be done by backtesting or papertrading no matter. Then you can say a selection's chance of winning is 20% i.e. between 17% and 23% with a certain degree of accuracy. Therefore you assume there is value in a price of 4.35 up to 5.80 , ( depending if you are looking to back or lay ). So when backing your price should be above 4.35 as that is your cut-off point based or your personal historic results. There is no point in using a generic table. Your edge, or value, is specific to your betting strategy/method and therefore your range in which you find value is not fixed but dependent on what and how you bet. I will fully agree that an understanding of the mechanism is essential if one wants to find profit.

[Gingertipster]

Re: Table Of Odds And Chances

Eh, do you mean 4.35 to mean 3.35/1? Because a 20% strike rate at 3.35/1 would show a defecit. A SR of better than 23% is needed at 3.35/1. A SR of better than 20% is needed at 4/1. Do not quite see your point Datapunter. Ginge

[Datapunter]

Re: Table Of Odds And Chances When i type 4.35 i mean 4.35 decimal odds, 1 / 4.35 = 0.23 therefore at a strike rate/win chance of 23% you break even. Above that there is profit, below it there is loss. My point is that if you estimate a win chance of 20% it is simply inaccurate to say there is no value under 5.00. For all you know the true chance might be 23% in which case there is value up to 4.35. ( or should that read down to ) The range you actually apply is determined by your historic results, however these are obtained. For those who want a quicky simply take your expected yield as margin. Setting a range to 0 as you seem to be doing is just as valid as setting the range to equal the expected yield for example. It simply depends on your method of determining the win chance.

[Gingertipster]

Re: Table Of Odds And Chances

When i type 4.35 i mean 4.35 decimal odds, 1 / 4.35 = 0.23 therefore at a strike rate/win chance of 23% you break even. Above that there is profit, below it there is loss. My point is that if you estimate a win chance of 20% it is simply inaccurate to say there is no value under 5.00. For all you know the true chance might be 23% in which case there is value up to 4.35. ( or should that read down to ) The range you actually apply is determined by your historic results, however these are obtained. For those who want a quicky simply take your expected yield as margin. Setting a range to 0 as you seem to be doing is just as valid as setting the range to equal the expected yield for example. It simply depends on your method of determining the win chance.

I realise my estimate may be out by a certain percentage but to back a horse at 100/30 that you estimate is a 20% 4/1 chance sees folly to me. If there is a 5 horse race, the bookie believes every horse to have the same chance 20%. He adds the mark up and offers 7/2 all 5 runners (working to 111%). Under your betting practices backing any 20% horse at as short as 100/30 you would back all the runners. A certain defecit. To work with a plus or minus inacurracy rate of 3% either way then you have to work the tissue out to a smaller percentage (not 100%). Depending on how many runners there are in the race. I have heard (whether it is right I do not know) Dave Nevison often works the percentages out to less than 100% (around 90 or 95%) for an inaccurracy rate. This may well be a good idea and cuts down on the number of bets a punter has.

[Datapunter]

Re: Table Of Odds And Chances

If there is a 5 horse race, the bookie believes every horse to have the same chance 20%. He adds the mark up and offers 7/2 all 5 runners (working to 111%). Under your betting practices backing any 20% horse at as short as 100/30 you would back all the runners. A certain defecit.

I'm not saying there is value on each horse or even a single horse. I'm saying there COULD be value on any of these horses as low as 100/30. Depending on your selection method and historic results. You simply DON'T KNOW if your 20% is accurate. ( nor does the bookie ) The only thing you can know is the result of your betting in the past, that tells you how accurate, as in a range, you have been. All you do is: a) shifting your range completely to one side. b) setting your range to 0. c) assuming you are 100% accurate in your estimations. depending what interpretation suits you (the reader) best. That does not mean a different interpretation and application of the concept of value is "folly" . It is simply different. And since we're on to bookies. I do hope you realise bookies don't care who wins a race. In fact they couldn't care less. They may even give punters a price at which they think they may be giving away value. :unsure Knowingly. :loon

[Gingertipster]

Re: Table Of Odds And Chances I am not saying a horse that I believe has a 20% chance definately has a 20% chance. If another punter believes it has a 23% or even 10% chance he could be right, I might be right, the bookie might be right. I think we basically agree. But to back a 100/30 shot when you BELIEVE it is a 20% chance is folly. Whatever your acurracy rate. For the reasons I have said. What is this different concept of value that makes it possible to make a profit on your bets at 100/30 with a 20% SR? It is surely impossible, the mathematics of betting do not allow it. Only by consistantly making a profit do you know you are getting value, at least most of the time. Though nobody KNOWS whether one individual selection is value or not. All we can do is estimate. Bookies do care who wins, very few win the same amount whoever wins. If we are talking about on course bookies. Some like Freddie Williams will in effect back a horse to win by offering a far shorter price than others. Off course bookies usually make more if an outsider wins than a favourite. Though essentially they have few horses in a race who are losers in their book. Of course no bookie works to less than 100%.

[Datapunter]

Re: Table Of Odds And Chances

I think we basically agree.

We do actually :rollin There's no argument about the maths, discussing that would be like discussing gravity, it is what it is. There are however various methods of bringing the basic maths into a real-life betting strategy, unless the priciple of "value" is completely ignored, all of them are of equal value (;)) because they all come down to the same principle. Anyhow, thanks for the table, the effort is appreciated. ( ermmm.... won't actually be using it as i am capable of dividing 1 by a number :spank )