Retrospective - API Release To Prevent Minimum Bet Abuse - 19th June

[WTPooh]

Hi Neil,

Both your formulae don't work in all cases, if you take some price/size combinations that are exactly on -20% or +25% some are allowed and some are blocked.

Price: 1.01 Size:0.80 Diff: 25% Allowed satisfies >=25%
Price: 1.10 Size:0.25 Diff: -20% Allowed satisfies <=-20%

but

Price: 1.01 Size:1.25 Diff: -20% Blocked satisfies < -20%
Price: 1.05 Size:0.25 Diff: -20% Blocked satisfies < -20%

there are other examples of this.

Can you give us a working formula that works in all cases and/or a list of price/size combination from 1.01 to say 3.0 and whether each size is allowed or blocked (Sizes up to £1.60 should be okay) ? For example £0.01 is allowed at 1.80 but is blocked again between 2.26 and 2.58.

We are trying to apply fixes but have inconsistent info which is often contradictory and has edge cases that doesn't work.

Thanks.

Your calculations of difference are incorrect. Here is simple C# function for lay bets:

double GetDiff(double price, double size)
{
var liability = Math.Round(size * (1 - price), 2, MidpointRounding.AwayFromZero);
var actualProfitRatio = size / liability;
var fairProfitRatio = 1 / (1 - price);
return Math.Round(actualProfitRatio / fairProfitRatio - 1, 4);
}

Currently allowed -0.20 <= diff < 0.25

[levelsoft]

Apologies for the terrible format, but anyone willing to verify these results for a under min lay bet

{
"stake required in pence":
odds to use in initiating under min bet size (doesn't have to be absolute smallest as long as it works)
}



{
"1":1.8,
"2":1.41,
"3":1.27,
"4":1.21,
"5":1.17,
"6":1.14,
"7":1.12,
"8":1.1,
"9":1.09,
"10":1.08,
"11":1.08,
"12":1.07,
"13":1.07,
"14":1.06,
"15":1.06,
"16":1.05,
"17":1.05,
"18":1.05,
"19":1.05,
"20":1.04,
"21":1.04,
"22":1.04,
"23":1.04,
"24":1.04,
"25":1.04,
"26":1.04,
"27":1.03,
"28":1.03,
"29":1.03,
"30":1.03,
"31":1.03,
"32":1.03,
"33":1.03,
"34":1.03,
"35":1.03,
"36":1.03,
"37":1.03,
"38":1.03,
"39":1.03,
"40":1.02,
"41":1.02,
"42":1.02,
"43":1.02,
"44":1.02,
"45":1.02,
"46":1.02,
"47":1.02,
"48":1.02,
"49":1.02,
"50":1.02,
"51":1.02,
"52":1.02,
"53":1.02,
"54":1.02,
"55":1.02,
"56":1.02,
"57":1.02,
"58":1.02,
"59":1.02,
"60":1.02,
"61":1.02,
"62":1.02,
"63":1.03,
"64":1.03,
"65":1.03,
"66":1.03,
"67":1.03,
"68":1.03,
"69":1.03,
"70":1.03,
"71":1.03,
"72":1.03,
"73":1.03,
"74":1.03,
"75":1.04,
"76":1.04,
"77":1.04,
"78":1.04,
"79":1.04,
"80":1.01,
"81":1.01,
"82":1.01,
"83":1.01,
"84":1.01,
"85":1.01,
"86":1.01,
"87":1.01,
"88":1.01,
"89":1.01,
"90":1.01,
"91":1.01,
"92":1.01,
"93":1.01,
"94":1.01,
"95":1.01,
"96":1.01,
"97":1.01,
"98":1.01,
"99":1.01,
"100":1.01,
"101":1.01,
"102":1.01,
"103":1.01,
"104":1.01,
"105":1.01,
"106":1.01,
"107":1.01,
"108":1.01,
"109":1.01,
"110":1.01,
"111":1.01,
"112":1.01,
"113":1.01,
"114":1.01,
"115":1.01,
"116":1.01,
"117":1.01,
"118":1.01,
"119":1.01,
"120":1.01,
"121":1.01,
"122":1.01,
"123":1.01,
"124":1.01,
"125":1.04,
"126":1.04,
"127":1.03,
"128":1.03,
"129":1.03,
"130":1.03,
"131":1.03,
"132":1.03,
"133":1.03,
"134":1.03,
"135":1.03,
"136":1.03,
"137":1.03,
"138":1.03,
"139":1.03,
"140":1.02,
"141":1.02,
"142":1.02,
"143":1.02,
"144":1.02,
"145":1.02,
"146":1.02,
"147":1.02,
"148":1.02,
"149":1.02,
"150":1.02,
"151":1.02,
"152":1.02,
"153":1.02,
"154":1.02,
"155":1.02,
"156":1.02,
"157":1.02,
"158":1.02,
"159":1.02,
"160":1.02,
"161":1.02,
"162":1.02,
"163":1.03,
"164":1.03,
"165":1.03,
"166":1.03,
"167":1.03,
"168":1.03,
"169":1.03,
"170":1.03,
"171":1.03,
"172":1.03,
"173":1.03,
"174":1.03,
"175":1.04,
"176":1.04,
"177":1.04,
"178":1.04,
"179":1.04,
"180":1.01,
"181":1.01,
"182":1.01,
"183":1.01,
"184":1.01,
"185":1.01,
"186":1.01,
"187":1.01,
"188":1.01,
"189":1.01,
"190":1.01,
"191":1.01,
"192":1.01,
"193":1.01,
"194":1.01,
"195":1.01,
"196":1.01,
"197":1.01,
"198":1.01,
"199":1.01,
"200":1.01

}

[Sansa]

I would say it is impossible to verify anybody's results at present. Neil has confirmed that there are currently inconsistencies, hence a fix is due next week. If you base your results on what is currently happening then that may all change after the fix. Without a detailed specification of what should be correct we cannot be 100% all is going to work as we expect after the fix. It is clear from this thread that people still interpret what information we have in different ways. My results differ from yours in many cases, I am not saying yours won't be accepted, but a lower price may be acceptable e.g. 0.04 @ 1.20. Yours may be the minimum for Backing, mine may be for Laying. Neil's example of an inconsistency was between a Back and a Lay bet, same size and price, one accepted but the other rejected. I interpreted this as they should be treated the same.

[levelsoft]

I would say it is impossible to verify anybody's results at present. Neil has confirmed that there are currently inconsistencies, hence a fix is due next week. If you base your results on what is currently happening then that may all change after the fix. Without a detailed specification of what should be correct we cannot be 100% all is going to work as we expect after the fix. It is clear from this thread that people still interpret what information we have in different ways. My results differ from yours in many cases, I am not saying yours won't be accepted, but a lower price may be acceptable e.g. 0.04 @ 1.20. Yours may be the minimum for Backing, mine may be for Laying. Neil's example of an inconsistency was between a Back and a Lay bet, same size and price, one accepted but the other rejected. I interpreted this as they should be treated the same.

Thanks Sansa.

I agree about the fact that this is guesswork but I have to try and work with something until the info is cleared up.

These are for lays. Perhaps I miss labelled the price. I'm not bothered about it being the absolute lowest (to within 2/3 ticks anyway), as long as they'll all work and not be rejected is the key. I'm just replacing the 1.01 with whatever works and I don't much care what it is. Bets that don't qualify like wanting to lay 2p as 1.27 is just a new rule that doesn't affect my apps in any real way, in fact due to the fact its all non attended I make sure the current odds aren't within 10 ticks of the order price to avoid possible full £2 bet match.

[BetfairDeveloperProgram]

Hi All,

This morning we made a release to fix the price/size inconsistencies that were reported previously.

Working formula on prices/sizes is most easily described from the Back point of view where rounding that causes <= 20% loss or <= 25% gain will be allowed.

Kind Regards

Neil

[Gamblr]

Working formula on prices/sizes is most easily described from the Back point of view where rounding that causes <= 20% loss or <= 25% gain will be allowed.

I'm a little bit confused about this. From the back point of view, how could rounding cause <=20% loss?

[winterwooksie]

Anybody got a spreadsheet that you plug values into ? Struggling with the lay side of things

[Sansa]

I believe it is the same for BACK and LAY.

		ACTUAL VALUE =	ROUNDED VALUE =
STAKE	PRICE	STAKE * (PRICE – 1)	ROUND(STAKE * (PRICE – 1),2)	ROUNDED / ACTUAL VALUE	(ROUNDED / ACTUAL) – 1
£0.01	2.24	0.0124	£0.01	0.8065	-0.1935	<20% Loss	Accepted
£0.01	2.26	0.0126	£0.01	0.7937	-0.2063	>20% Loss	Rejected
£0.01	1.79	0.0079	£0.01	1.2658	0.2658	>25% Gain	Rejected
£0.01	1.8	0.008	£0.01	1.2500	0.2500	25% Gain	Accepted
£0.01	1.81	0.0081	£0.01	1.2346	0.2346	<25% Gain	Accepted