When there is only one round of betting left and only
one card to come, comparing your chances of improving
to the pot odds you are getting is a relatively straightforward
proposition. If your chances of making a hand you
know will win are, say, 4-to-1 against and you must
call a $20 bet for the chance to win a $120 pot, then
clearly your hand is worth a call because you're getting
6-to-1 pot odds. Those 6-to-1 odds the pot is offering
you (excluding bets on the end) are greater than the
4-to-1 odds against your making your hand. However,
when there is more than one card to come, you must
be very careful in determining your real pot odds.
Many players make a classic mistake: They know their
chances of improving, let's say, with three cards
to come, and they compare those chances to the pot
odds they are getting right now. But such a comparison
is completely off the mark since the players are going
to have to put more money into the pot in future betting
rounds, and they must take that money into account.
It's true that the chances of making a hand improve
greatly when there are two or three cards to come,
but the odds you are getting from the pot worsen.
In split-pot games, a minimum holding required to
win half the pot. Qualifiers are much more common
on the low side (for example, an eight-low can qualify
for the low side of a pot, while a nine-low can't),
but occasionally you run into high qualifiers.
(2) In a draw game, a minimum holding required to
initiate the betting, as jacks or better.