calculating equity from outs - Gambling and Probability

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calculating equity from outs

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08-18-2010 , 07:01 PM

stokkbroker

journeyman

Join Date: Jan 2010 Posts: 238

Hi

I cant remember the 100% correct way of calculating equity from outs.

I am used to using the "4x on flop and 2x on turn"-rule, but I know that`s not 100% correct.

What is it that I have to add or substract on flop / turn to get it 100% correct?

Thanks.

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08-18-2010 , 10:14 PM

spadebidder

Actually Shows Proof

Join Date: Aug 2008 Posts: 7,905

Quote:

Originally Posted by stokkbroker

There is no 100% correct way unless you know opponents cards. But I think what you want is the adjustment to make the rule of 4 more accurate for the chance to hit your outs. Don't confuse that with "equity", it isn't the same. It's just the chance to hit your outs, which you are speculating will give you the win.

Using the rule of 4 you should subtract 1% for every out over 8. So with 9 outs, use 9*4 = 36, minus 1 = 35%. Or with 12 outs use 12*4 = 48 minus 4 = 44%.

The rule of 2 (one card to come) is good enough with no adjustment. It's just using 50 for the denominator instead of the actual 46 or 47, which is harder to do in your head.

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08-18-2010 , 11:32 PM

Geniius

journeyman

Join Date: Feb 2010 Posts: 367

If you don't know your opponents cards, divide your outs by 0.

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08-19-2010 , 12:01 AM

RustyBrooks

Carpal \'Tunnel

Join Date: Feb 2006 Posts: 24,647

Quote:

Originally Posted by Geniius

If you don't know your opponents cards, divide your outs by 0.

Wat?

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08-19-2010 , 12:18 AM

Geniius

journeyman

Join Date: Feb 2010 Posts: 367

Quote:

Originally Posted by RustyBrooks

Wat?

obv jk my tx friend.

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08-19-2010 , 01:31 AM

Sherman

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Join Date: Jun 2005 Posts: 7,766

Quote:

Originally Posted by Geniius

If you don't know your opponents cards, divide your outs by 0.

I LOL'd.

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08-19-2010 , 03:31 PM

stokkbroker

journeyman

Join Date: Jan 2010 Posts: 238

Quote:

Originally Posted by spadebidder

Thats what I was looking for, thanks.

And yeah, obviously I meant chance of hitting outs, not equity.

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08-21-2010 , 12:23 PM

BruceZ

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Join Date: Sep 2002 Posts: 11,877

Quote:

Originally Posted by stokkbroker

Thats what I was looking for, thanks.

That adjustment isn't 100%, even assuming random opponent's cards. These are exact formulas, assuming random opponent's cards:

TURN:

P(hit on river) = outs/46

FLOP:

P(hit on turn or river) =

1 - (1 - outs/47)*(1 - outs/46)

or

outs/47 + (1 - outs/47)*outs/46

or

2*outs/47 - [outs/47 * (outs-1)/46]

or

outs/47 + outs/46 - (outs/47 * outs/46)

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