Betfair cross matching explained!
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I think it's easiest to see on 1.01 on horse races dallas. If you watch closely sometimes you will see say 2-4k waiting on the lay side and then all of a sudden 22k is matched. I imagine this will be explained as a refresh issue but it should be reasonably easy to see.
I'm a bit confused by how matched volume is computed for cross matching.LeTiss 4pm wrote:If I back Djokovic for £30 at 1.50, but only £20 is available, the other £10 might come from laying a backer of Federer at 3.00
According to BF my £30 would show £40 matched on Djokovic and £20 Federer, as opposed to what I'd expect to see, which is £60 matched on Djokovic
This doesn't explain though why I can see my bet sat waiting on a selection, and the matched figure for that selection is indicating I should be getting matched, but am not
Say I want to back Djokovic for £10 at 1.50.
Situation 1: There is a layer of Djokovic that matches this, then as I understand it the matched volume on Djokovic goes up by £20.
Situation 2: There are no layers of Djokovic, but instead I'm cross matched to lay a backer of Federer for £5 at 3.00.
How much does the volume on Federer go up in this case? I suppose if I was "originally" a layer here it would go up by £10 (twice backer's stake), but is it now the case that since I'm "originally" a backer of £10, it would go up by £20 (twice "original" backer's stake)?
2 selections are easy to understand and accept Peter. Where XM starts to become a grey area is when there's 3 + selections, as it becomes unclear as to who is getting matched and why. I don't like that, it makes the matching process look like it's being tampered with
Yeah, that's a great point actuallyPeterLe wrote:Yes I agree..
Also for anyone using automated strategies; you can see how things (EG WOM) is shown differently depending upon whether you have it switched on of off.. so could help or hinder a strategy..
I've come to realise over the years that WOM is quite often a trap, as much as a guide.
https://www.youtube.com/watch?v=3njy483sL-wPeterLe wrote:Cross matching was introduced on the 24th Nov 2010 (?) and I remember the build up wondering what would happen (there is a tread on here somewhere)
This explains what it is and is the best explanation Ive seen:-
https://api.developer.betfair.com/servi ... rtual+Bets
Although its a straight forward calcualtion; it seems to behave differently these days that when introduced originally.
Here is a video I did at the time (Pause the video as it plays and you can compare the subtle differencesin odds/money avail at those odds between one account with Cross Matching and one account with no cross matching)
https://www.youtube.com/watch?v=3njy483sL-w
Once you understand how it works; you will drive yourself mad trying to work out how to exploit it!
i saw this link
it's really hard to understand formula..and it's really really hard to undersand why in a moment(13seconds)the lay odds of third is different(4,1no xm-4,2 whit xm )
the book percentage is 101.5 for the lay column in that moment(and backers column is under 100percentage!), why the odds up?
ps:I think the key to understanding why the odds when they take you take you systematically disadvantage 'to look for in this cross-matching (english is not my language )
Folks,
Pre API-NG, Betfair had a doc that explained the cross matching principle, they had a example based on a football match and accompanying it they had a formula.
Does anyone have a copy of that formula please? (betfair still have examples of cross matching but they seem to have removed the formula)
I know betfair cross match against linked markets, I know that, but Im just looking for that original formula, if anyone can help
Thanks in advance
regards
Peter
Pre API-NG, Betfair had a doc that explained the cross matching principle, they had a example based on a football match and accompanying it they had a formula.
Does anyone have a copy of that formula please? (betfair still have examples of cross matching but they seem to have removed the formula)
I know betfair cross match against linked markets, I know that, but Im just looking for that original formula, if anyone can help
Thanks in advance
regards
Peter
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- Posts: 3140
- Joined: Sun Jan 31, 2010 8:06 pm
1 / (N –∑ 1/(best to lay price of other runners))
Where N is the number of winners that market will have, e.g. for a “to win” market N = 1, for a place market with 3 winners N = 3.
For each runner calculate the available stake at that price as:
MIN(odds1*stake1, odds2*stake2...oddsn*staken) / [the price calculated in step a. above]
In plain English the stake you can match is limited by the payout (odds*stake) available on each of
the component bets that you’d need to match.
Where N is the number of winners that market will have, e.g. for a “to win” market N = 1, for a place market with 3 winners N = 3.
For each runner calculate the available stake at that price as:
MIN(odds1*stake1, odds2*stake2...oddsn*staken) / [the price calculated in step a. above]
In plain English the stake you can match is limited by the payout (odds*stake) available on each of
the component bets that you’d need to match.
Last edited by spreadbetting on Wed Jun 27, 2018 7:17 pm, edited 1 time in total.
Hispreadbetting wrote: ↑Wed Jun 27, 2018 6:55 pm1 / (N –∑ 1/(best to lay price of other runners))
As far as I can remember.
Thanks for the reply; (good memory! ) Yes I just found it too...Extract below
For the available to back prices on the LHS:
• For each runner calculate the best price at which you could effectively back that runner by
laying all the others:
1 / (N –∑ 1/(best to lay price of other runners))
Where N is the number of winners that market will have, e.g. for a “to win” market N = 1, for a place
market with 3 winners N = 3.
• For each runner calculate the available stake at that price as:
MIN(odds1*stake1, odds2*stake2…oddsn*staken) / [the price calculated in step a. above]
In plain English the stake you can match is limited by the payout (odds*stake) available on each of
the component bets that you’d need to match.
• Repeat from the first step above
Taken from : http://www.bettingdeveloper.org/docs/Be ... 0Guide.pdf