[colgin]

[ QUOTE ]
it most certainly is the worst mistake (i specifically said magnitude) though just as certainly not the most common. Folding a winner on the end is real bad, folding a winner on the end after aggressively putting money in on the river is the worst single mistake you can make.

[/ QUOTE ]

Folding a winner to a river raise is a HUGE mistake only if you have grossly misestimated how often your hand is good given the board, your opponent's hand range and his bluffing frequency, etc. For example, if you fold to the river raise getting 8:1 because you correctly evaluate that your hand isn't good even 10% of the time then your fold is a good one. (And that is regardless of results; if your evaluation was correct but your opponent were to show you his worse hand (one of the few wrose hands you thought he could have had) after you folded then your fold would still have been good.)

However, if your assumptions and judgments are way off and your hand is good 30+% of the time then you have made a sizable mistake by folding. I think it is fine when in doubt to lean towards calling; but don't assume that your fold, if it is a mistake at all, is necessarily huge one. It may, in fact, be very close EV-wise one way or the other.