Poker Ev

Neko67

Neko67

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Hey everyone.
I'm still trying to get the concepts of EV and reading The Theory of Poker by David Sklansky. However I'm kind of confused when trying to combine the EV formula with his examples.
So one where I got confused was that there 5 numbers on a paper and someone bet you: $5 for a wrong guess and $1 for a right guess. And in the book it said a negative EV of $2
I'm confused on how he is getting this number.
If anyone would pm me so we could talk more that be great. But any replies would be helpful as well. Thanks guys!
 
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braveslice

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This is good read: http://www.thepokerbank.com/strategy/mathematics/expected-value/calculate/

Your example is a bit unclear for me, but there is no way to get negative 2. I guess questions means player in this case is a dealer?

If so:
Probability you win 80% (four out of five, table wins), Pwin, and you win 1 dollar
EVwin=Pwin*$1 = 0.8*$1 = $0.8

Probability you lose 20% (1 out of five), Plose, and you lose 5 dollars
EVlose=Plose*5$=0.2*$5 = $1

Total ev:
EV = EVwin – EVlose = $0.8 - $1 = -$0.2
I think they just tested if you are awake ;) or saved some space by not including zero to the answer.
 
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Neko67

Neko67

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This is good read: http://www.thepokerbank.com/strategy/mathematics/expected-value/calculate/

Your example is a bit unclear for me, but there is no way to get negative 2. I guess questions means player in this case is a dealer?

If so:
Probability you win 80% (four out of five, table wins), Pwin, and you win 1 dollar
EVwin=Pwin*$1 = 0.8*$1 = $0.8

Probability you lose 20% (1 out of five), Plose, and you lose 5 dollars
EVlose=Plose*5$=0.2*$5 = $1

Total ev:
EV = EVwin – EVlose = $0.8 - $1 = -$0.2
I think they just tested if you are awake ;) or saved some space by not including zero to the answer.
Thanks for the reply I appreciate it. I read that article too. The formula makes sense to me its just other applications don't seem to add up sometimes. Here's a screenshot of the example. Its starts at the very top of the pic. Thanks again
80a850d298f53b3d32574775482813a8.jpg
 
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braveslice

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Ok, so from the book this is just standard case, not like I understood in earlier post

So in your question example odds are 4-to-1 against you:


Probability you win 20% (four out of five), Pwin, and you win 5 dollar
EVwin=Pwin*$1 = 0.2*$5 = $1

Probability you lose 80% (one out of five), Plose, and you lose 1 dollars
EVlose=Plose*1$=0.8*$1 = $0.8

Total ev:
EV = EVwin – EVlose = $1 - $0.8 = $0.2
So your expectation is plus 20 cents per bet, precisely as stated in the book.


The line that confuses you with 2 dollar negative EV is not the same problem than above and what you asked. The question for that is as follows:

Your odds are 4-to-1 favorite, you bet 50 to win 10, calculate EV


Frist from odds to % -> 1/4[odd] -> 1/(4+1)[%] -> 1/5 -> 0.2 -> 20% (you lose 20% of time)

Probability you win 80% (four out of five), Pwin, and you win 10 dollar
EVwin=Pwin*$1 = 0.8*$10 = 8$

Probability you lose 20% (one out of five), Plose, and you lose 50 dollars
EVlose=Plose*50$=0.2*$50 = $10

Total ev:
EV = EVwin – EVlose = $8 - $10 = - $2

Very badly written text, but that is normal because proofreaders are totally clueless on math side, so they just give up. Also odds format should be forbidden, at least from basic tutorials, it’s there only to confuse you.
 
Neko67

Neko67

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Ok, so from the book this is just standard case, not like I understood in earlier post

So in your question example odds are 4-to-1 against you:


Probability you win 20% (four out of five), Pwin, and you win 5 dollar
EVwin=Pwin*$1 = 0.2*$5 = $1

Probability you lose 80% (one out of five), Plose, and you lose 1 dollars
EVlose=Plose*1$=0.8*$1 = $0.8

Total ev:
EV = EVwin – EVlose = $1 - $0.8 = $0.2
So your expectation is plus 20 cents per bet, precisely as stated in the book.


The line that confuses you with 2 dollar negative EV is not the same problem than above and what you asked. The question for that is as follows:

Your odds are 4-to-1 favorite, you bet 50 to win 10, calculate EV


Frist from odds to % -> 1/4[odd] -> 1/(4+1)[%] -> 1/5 -> 0.2 -> 20% (you lose 20% of time)

Probability you win 80% (four out of five), Pwin, and you win 10 dollar
EVwin=Pwin*$1 = 0.8*$10 = 8$

Probability you lose 20% (one out of five), Plose, and you lose 50 dollars
EVlose=Plose*50$=0.2*$50 = $10

Total ev:
EV = EVwin – EVlose = $8 - $10 = - $2

Very badly written text, but that is normal because proofreaders are totally clueless on math side, so they just give up. Also odds format should be forbidden, at least from basic tutorials, it’s there only to confuse you.
I see where your going with that but how can the probability of winning go from 20% to 80%? Bc you only win if you pick 1 of the 5 numbers
 
Neko67

Neko67

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I see where your going with that but how can the probability of winning go from 20% to 80%? Bc you only win if you pick 1 of the 5 numbers
OHHHH I see what you mean. The difference between odds against and in your favor. But what is the difference?
 
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braveslice

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Well odds are made by people who have no idea bout mathematics, made by drunkers probably in pubs in old England who did not know how to write their names. So you will never see the equations directly, just try to go around it by using common sense.


1:2 odds against means you win one time and lose 2 times. Thus out of 3 times you will lose 2 times. Just pick the bigger number. Against=lose=bigger number


1:2 odds in favor means you will win 2 times and lose 1 time. Thus out of 3 times you will lose one time. Just pick the bigger number. Favor=win=bigger number.
 
Neko67

Neko67

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Well odds are made by people who have no idea bout mathematics, made by drunkers probably in pubs in old England who did not know how to write their names. So you will never see the equations directly, just try to go around it by using common sense.


1:2 odds against means you win one time and lose 2 times. Thus out of 3 times you will lose 2 times. Just pick the bigger number. Against=lose=bigger number


1:2 odds in favor means you will win 2 times and lose 1 time. Thus out of 3 times you will lose one time. Just pick the bigger number. Favor=win=bigger number.
Alright thanks man. Its mucu clearer now. 😸
 
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