You are playing in your regular Thursday-night poker game, dealer's choice, and the game is 7-card stud, high only. You have a pair of Aces showing, the second received as the fifth card. You have been making normal-size bets, and after the seventh card has been dealt, there are still three others in the hand. You find that despite a number of possibilities, your hand has not improved. You consider making a bet to suggest you have at least two pair but decide instead to check. There is $50 in the pot. Duke, sitting to your left, also checks, but Bill bets the maximum allowed, and Ty folds. Now it's up to you. You . . .

Do you fold, call, or raise? That depends on several crucial pieces of information, some of which you would already have as a player, though they were not mentioned above.

First, how big is the bet, and what are the betting rules? On the one hand, if Bill bet $2 because this is a $2-limit poker game, that is a small amount to spend to possibly win $52. Because a pair of Aces or worse will prove to be the winning hand in more than one twenty-sixth of all deals in 7-card stud, it would be foolish to fold in the face of what might be a bluff. On the other hand, if the game is pot limit, and the bet is $50, you would be risking $50 to possibly win $100, and the probability of a pair of Aces being the high hand is far less than one in three. This illustrates one of the guiding principles of playing poker: pot odds are crucial to determining what to do. In turn, this means that you have to pay attention to the relationship among the probability of holding the winning hand, the amount you expect to spend to be in on the call, and the amount you expect to win if you have the winning hand. The last two of these factors depend crucially on the betting rules and the stakes of the game. Anyone who tells you that you should always call or always drop with a given hand can't be right-though i...