"You need to be good X% of the time here"... How do you estimate this?

[JerseyTom]

Here's a hand from today that got me thinking: exactly how do people estimate how often your hand is good in a certain situation? And I mean in terms of numbers (realizing of course that it's impossible to do this exactly).

Here's the hand:

Read on MP1 is very shallow: 64/0/3.22 over 14 hands

Party Poker 2/4 Hold'em (10 handed) converter (http://www.selachian.com/tools/bisonconverter/hhconverter.cgi)

Preflop: JerseyTom is MP3 with K/images/graemlins/diamond.gif, Q/images/graemlins/club.gif. MP1 posts a blind of $2.
<font color="#666666">3 folds</font>, MP1 (poster) checks, <font color="#666666">1 fold</font>, <font color="#CC3333">JerseyTom raises</font>, <font color="#666666">2 folds</font>, SB calls, BB calls, MP1 calls.

Flop: (8 SB) 2/images/graemlins/club.gif, 8/images/graemlins/spade.gif, K/images/graemlins/spade.gif <font color="#0000FF">(4 players)</font>
SB checks, BB checks, MP1 checks, <font color="#CC3333">JerseyTom bets</font>, SB calls, BB folds, MP1 calls.

Turn: (5.50 BB) 7/images/graemlins/spade.gif <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">MP1 bets</font>, JerseyTom...

OK, MP1 bets out the scare card here. Given that he plays all kinds of junk, he could have:

- a flush (I'm drawing dead)
- slowplayed a medium set (I'm drawing dead)
- turned 2 crappy pair (I may have outs with a K, Q 8 or 2 depending on what he has)
- nothing at all

The easy part of this is figuring out how much it costs to call down (lets assume SB folds the turn to simplify things). It's going to cost me 2 more BB to win 7.5 if I call down, so my hand needs to be good more than 21% of the time for this to be right.

But how do you calculate that 21%? Suggestions welcome.

[gaming_mouse]

This is easy.

Your odds are 7.5:2. So your hand must be good

2/(7.5+2)=21% of the time.

You can generalize from this example too.

gm

[JerseyTom]

Thanks, mouse, but I was going for something a lot more subtle here: i.e., how does one calculate/consider the likelihood of each of the above hands. I realize this is a very fuzzy question - the answer depends a lot on the opponent, the stakes, etc.


Tom