Odds Calcuation Concept

[RobTheCrook]

I was thinking about this the other day after a problem I had in a tournament.

It was late in a tournament with about 25 people, approaching the bubble. I raised in late position with J5s to steal the blinds, and the BB came over the top for all his chips. I did a quick pot odds calculation, and after determining I was getting over 3:1 I called.

After the flop I realized I had made an error and my opponent was not all in. He had put about half his chips into the pot. Obviously when the flop came, he pushed the rest of his chips in. I had missed the flop completely and had to fold

My question is, if an opponent makes a strange raise like this before the flop, and you know for a fact that he will be pushing all his chips in first to act when the flop comes, how do you determine the total pot odds are you getting? And what is the difference in the odds calculation considering you also get to see the flop before committing the rest of the chips, but you aren't going to see all five cards for a fixed price before the flop?

[infinity235]

If you are considering betting on future streets, you are talking about the concept of implied odds. In this case, you were getting 1:1 effective odds(or close to it) because you needed to match BB's stacks size in order to win his stack (because you are sure he was gonna push on the flop anyway) This means you need a hand that has at least 50% pot equity against any random hand (or a range, if you have a read).

[AaronBrown]

Let P be the amount in the pot if he just calls your preflop bet. Let B1 be the amount he raises preflop, and B2 be the minimum remaining amount between your two stacks. If you call preflop, three things can happen:

(1) You fold after the flop and lose B1 (of course, you also lose your first preflop bet, but that's a sunk cost when you're making the decision to call his preflop raise).

(2) You call after the flop and lose. Now you lose B1 + B2.

(3) You call after the flop and win. Now you win P + B1 + B2.

You have to work these problems backward. You'll only call after the flop if your chance of winning, p, is greater than:

p > B2/(P + 2*B1 + 2*B2)

Let q be the probability of getting a flop such that p is big enough to call, and d be the average excess p (that is, given that the flop gives you a high enough p to call, how much that p is above the minimum p). Your expected value after the flop is dealt is:

q*d*(P + 2*B1 + 2*B2)

If this is larger than B1, you have positive EV by calling.

As a practical matter, you don't have to get this complicated. With J5s, for example, you might call if you get two matching suits on the flop or if there are no Aces or face cards, but you don't have a lot of positive EV with those calls. You might get the flush or an OESD on the flop, but those don't happen very often. Most of your positive expectation comes from getting a J with no Aces or other face cards, or JJ, 55 or J5. So you can just do the calculation for those hands, then if it's a close call, add a little bit for the other possibilities.

[Check2TheLady]

Can I just point out that this raise more than likely puts your opponent on a monster starting hand? He is giving you 3:1 odds out of position after you have shown strength with your raise. This is very risky with a hand like JJ or AK. I would say that he has QQ at the very least and it reeks of aces.

Therefore I would say that you are not getting the right odds at this point and could probably fold pre flop (you are more than a 4:1 dog in this situation.) Although, of course, this means that the implied odds are there, but imo you should be aware that you are playing for two pair or better on the flop.

Perhaps someone who accepts this analysis, but is better at maths than myself, could work out whether a call pre-flop would be justified given that:

a) Your opponent has AA or KK
b) You will call his all-in on the flop only if you have 2 pair or better (and then may still get outdrawn) or a draw to a flush or straight.

My instinct would be to fold, particularly in a tournament, as there are too many things that could go wrong in this situation and I wouldn't want to get too clever with my J5, but I would be interested to know what the 'answer' would be.

I would also be interested to know if anyone agrees / disagrees with my analysis and the tight range that I am putting your opponent on?

[binions]

[ QUOTE ]
Can I just point out that this raise more than likely puts your opponent on a monster starting hand?

[/ QUOTE ]

I see this raise a lot with AK. And it does a helluva job convincing AQ to push over the top.

[Check2TheLady]

If it were me it would be a push with AK, but I take your point, it is a possibility. Even so though, do you feel confident to call his all-in on a flop of J 10 3 rainbow? I would maintain that a fold would be the best play...