Author Topic: Formula Help  (Read 2073 times)

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Formula Help
« on: 30 Nov 2017, 08:02 »
Hi all,

I am trying to find what formula should be used for the following:

A 10£ lay bet was placed at 2.30. This bet will have a liability of 13£.

Now if I want to attempt to place a green up back back to get 5% of the liability (not stake) how can I calculate what odd and stake (including commission) should be used? i.e. 9.27£ at 2.48 for a 5.30% hedged profit.

From what I have understood the "attempt to green up" trigger will do the math for the stake and not liability.

Thanks

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Re: Formula Help
« Reply #1 on: 30 Nov 2017, 15:01 »
bp = lp/(1 - P*(lp-1)/(1-commission))

ba = lp*la/bp

Where: 

bp = back price
lp = lay price
ba = back amount
la = lay amount
P = profit percentage/100

See the example attached.
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Re: Formula Help
« Reply #2 on: 30 Nov 2017, 18:50 »
bp = lp/(1 - P*(lp-1)/(1-commission)) ba = lp*la/bp Where: bp = back price lp = lay price ba = back amount la = lay amount P = profit percentage/100 See the example attached.

Thank you very much Oxa

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Re: Formula Help
« Reply #3 on: 02 Jan 2018, 21:37 »
Hi @Oxa

Can you please help me understand how can I can calculate the next valid odd? This is especially true with odds of 2.00+ as the tick increment changes.

Example: lay odd 2.60, attempting to get 10% profit on a 5% commission market using the bp = lp/(1 - P*(lp-1)/(1-commission)) formula

2.60/(1-0.10*(2.60-1)(1-0.05)) = 3.126582 (back price)

Since there is no 3.12 odd the only near "valid odds" are 3.10 or 3.15.
I have tested and confirmed that MF will correctly calculate the valid odd (3.15= when placing a bet but this has an impact placing the correct amount to hedge using "ba = lp*la/bp" formula as the bp used to calculate was 3.126582.

Thanks

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Re: Formula Help
« Reply #4 on: 03 Jan 2018, 06:49 »
Hello!

The calculation error has to be factored into these formulae. BetFair will round a bet down to 0.01, so anything beyond that will be ignored and it can affect the P/L.
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Re: Formula Help
« Reply #5 on: 03 Jan 2018, 19:09 »
Hi

Any suggestion on how to achieve that?

I couldn't find a rounding function or something related to that. Perhaps using b_tick?

Thanks

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Re: Formula Help
« Reply #6 on: 08 Jan 2018, 15:02 »
The standard green-up trigger action is better at handing these errors, so it's better to use it rather than manual backing/laying.

The easiest way to get a 10% with 5% commission in mind is to factor that commission into the profit percentage (see the example trigger attached).
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Re: Formula Help
« Reply #7 on: 10 Jan 2018, 19:31 »
The standard green-up trigger action is better at handing these errors, so it's better to use it rather than manual backing/laying. The easiest way to get a 10% with 5% commission in mind is to factor that commission into the profit percentage (see the example trigger attached).

Hi Oxa,

Thanks for your reply.

I thought about using the green-up trigger as well. But as I mentioned in the first post "the "attempt to green up" trigger will do the math for the stake and not liability". So it's great for a back-first trade but not for a lay-first.

I even thought about placing a standard 2 bet just to check what the odd would be and then place a second bet with the reaming hedge amount.

Do you see any other viable option for this?

Thanks

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Re: Formula Help
« Reply #8 on: 23 Jan 2018, 21:05 »
No problem, you just adjust the profit percentage so that it reflects the liability. See the attached trigger.
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Re: Formula Help
« Reply #9 on: 03 Feb 2018, 14:37 »
Hi Oxa,

Thank you very much. It works as planned.

 

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