Looking through this thread, it feels like not everyone understands the importance of equity or properly understands what equity is.
Whether you call, raise, or fold depends largely in part on the size of the pot, effective stacks behind, SPR (size to pot ratio) and potential fold equity.
Due to equity, there may be situations in which you are behind but it is still profitable to call.
Lets take a look at two situations.
Hero is on the BTN with
, 3 limpers to him, Hero calls, SB and BB call. Eff stacks $200
Flop($14)
BB shoves for $200, everyone folds, action gets to hero. As Hero is thinking BB flashes Hero his cards and he has a set of sevens. BB says, "Yeah, I just want to take the pot down now, I don't want to get cracked" what should hero do?
Looking at pokerstove we see that Hero's equity is
Text results appended to pokerstove.txt
4,685,660 games 2.547 secs 1,839,678 games/sec
Board: Jh Qs 7s
equity win
Hand 0: 40.301% { Ts9s }
Hand 1: 59.699% { 7c7d }
We see that Hero has 40% equity. In order to be profitable Hero needs to be getting R = (1-E)/E = (1 - 0.4)/0.4 = 1.5
So Hero needs to be getting 1.5:1 on his money for a call to be profitable but unfortunately he is getting 214/200 = 1.07 on his money.
NOw lets look at that same situation but this time, BB shoves, MP shoves, and action is on Hero. This time, BB shows a set of sevens and MP shows AQ of diamonds. What should Hero do?
Well, looking at Poker Stove our equity improves a touch since MP has removed a fullhouse out
Text results appended to pokerstove.txt
7,973,167 games 5.703 secs 1,398,065 games/sec
Board: Jh Qs 7s
equity win
Hand 0: 41.758% { Ts9s }
Hand 1: 55.138% { 7c7d }
Hand 2: 03.104% { AdQd }
For the sake of argument, lets just give hero the same equity of 40% that he had in the first example. In order to be correct in calling Hero needs 1.5:1 on his money. But now, in this case, hero is getting (14 + 200 + 200) / 200 = 2.07
So in the second case, Hero is getting 2.07:1 on his money which is greater than the 1.5:1 on his money that he needs thus Hero should call. Yes, even though Hero is "behind" it is still profitable for him to make the call.
Now, take into account FOLD EQUITY. When Hero flops big draws like this, being aggressive on each street will usually generate fold equity. If your villain will fold 25%, 35%, or even 50% of the time when you show aggression on multiple streets then being aggressive with strong draws is INSANELY profitable.
Alot of beginners think that a draw is "Not a real hand" and that is the wrong way to think about it. Draws have equity. If you have enough equity then you need to call. If you sense weakness in your villains and/or you have a strong image that can generate fold equity then you need to play your draws aggressively. If you sense you have NO fold equity then you need correct odds to play your draws and if you are getting correct odds (direct and/or implied) you call and if you are not you fold.