Why you can't bet to give yourself better pot odds!
Let's say it is the final round of betting. The pot is $10, your equity vs your opponents range is 20% (a probability of 0.2 that we win) and you don't know what to do. You are first to act vs one opponent.
1) You check and your opponent checks:
Your Expectation = 0.2*($10) = $2.00
2) You bet $2 and your opponent calls:
Your Expectation = 0.2*($10 + $2 + $2) - $2 = $0.80
3) You check, your opponent bets $2 and you call:
Your Expectation = same as in 2)
4) You bet $2, your opponent raises it to $4 (he calls your $2 and adds $2 more), you call:
In this case, the raised pot totals $16 ($10 + $2 you add + $4 opponent puts in) and it costs you $2 to call -- that's 12.5% pot equity and you have 20% equity to win! But...
Your Expectation = 0.2*($10 + $2 + $2 + $2 + $2) - ($2 + $2) = -$0.40
If you want some sort of equation for Expectation, it's basically:
Expctation = (probability we win)*(size of new pot) - (what it costs you)
Things get more complicated when we're looking at catching draws and things on later streets, but i'll post on that eventually.
N.B. This is for those times are equity is less than 50%, since we want to bet/call (or bet/raise) when we have better than 50% equity.
Re: Why you can't bet to give yourself better pot odds!
Quote:
Originally Posted by loonychune
2) You bet $2 and your opponent calls:
Your Expectation = 0.2*($10 + $2 + $2) - $2 = $0.80
3) You check, your opponent bets $2 and you call:
Your Expectation = same as in 2)
You're not betting to win the money that you're betting.
Re: Why you can't bet to give yourself better pot odds!
Quote:
Originally Posted by loonychune
In this case, the raised pot totals $16 ($10 + $2 you add + $4 opponent puts in) and it costs you $2 to call -- that's 12.5% pot equity and you have 20% equity to win! But...
One other thing I felt was important enough to address. You state in the earlier examples that we have 20% equity when our bet is called, or when we check, he bets, and we call. However, this is a different situation. We are now not facing his betting range or calling range. We are now facing his raising range, which will likely differ from the above. Therefore, our equity is likely to also change. So it is very plausible that we no longer have 20% equity in this spot when we are facing a raise from villain, and this should be considered and factored into the calcs.
Re: Why you can't bet to give yourself better pot odds!
Quote:
Originally Posted by loonychune
In this case, the raised pot totals $16 ($10 + $2 you add + $4 opponent puts in) and it costs you $2 to call -- that's 12.5% pot equity and you have 20% equity to win! But...
Your Expectation = 0.2*($10 + $2 + $2 + $2 + $2) - ($2 + $2) = -$0.40
And yet here's something else. In the above, why are you subtracting $4? You have already made a bet, and you are now determining the ev of your call. Your bet has a different expected value than your call here.
So, the pot is $10. You bet $2, and villain raised to $4 (calls your $2 and puts in another $2). The pot is now $16, and you must call $2. Let's say you do have the 20% equity you stated when you call (just for example purposes. I've already stated that is might be incorrect to assume). Therefore, the ev of your call can be factored by the following formula:
Ev(call) = (equity)*(total pot) - (amount it cost)
Ev(call) = (0.20)*($18) - ($2)
Ev(call) = $1.60
OR
Ev(call) = (win %)*(amount we win) - (lose %)*(amount we lose)
Ev(call) = (.20)*(16) - (.80)*(2)
Ev(call) = (3.2) - (1.6)
Ev(call) = $1.60
The only difference is the extra $2 you added in. I don't see why adding that in would be correct.
Re: Why you can't bet to give yourself better pot odds!
Your not betting just so that a call is +EV, in this situation your betting because betting is +ev. And then when you are faced with the raise, the call is also +ev. Therefore, you make both decisions. Like I was saying, the ev of your bet and the ev of your call is separate of one another.
Quote:
Originally Posted by loonychune
In this case, the raised pot totals $16 ($10 + $2 you add + $4 opponent puts in) and it costs you $2 to call -- that's 12.5% pot equity and you have 20% equity to win! But...
Not sure how many more times I will quote this paragraph, but anyways. Can you explain where "12.5%" comes from? If the pot is $16 and it costs you $2 to make a call, then you need:
Ev(2call) = (amount to call) / (pot + amount to call)
Ev(2call) = (2) / (16 + 2)
Ev(2call) = 2/18 = 0.1111111 or 11%
Therefore, you need 11% equity in the pot to make a breakeven call. Given you have more than the needed equity in this situation, then a call is +ev.
I would just like to note, that it wasn't you that gave yourself correct odds to call, it was villain. His raise size just laid you too good of odds to pass up on. Had villain raised to a reasonable amount, then a call from you would have been -ev; however, the bet you made would have still be +ev. For example,
You have 20% equity. The pot is $10. You bet $2, and villain raises to $9 (calling your $2 and putting in $7 more). The pot is now $21 and you must call $7.
Ev(call) = (equity)(total pot) - (what it cost)
Ev(call) = (0.20)(28) - (7)
Ev(call) = -$1.40