Running It Twice (or More)

[East Bay Rounder]

In a cash game situation, why would someone ahead in a hand want to "run it twice"? To my knowledge, when this happens, the pot is split in two, so the winner of each "run" wins half the pot.

The way I see it, if you are a proponent of this, you'd lose money in the long run, plus you give the underdog an extra chance to win a pot he's behind in, without extra financial compensation.

Thoughts?

[tannenj]

you are 100% correct. nothing to add.

[Dan Terra]

[ QUOTE ]
you'd lose money in the long run

[/ QUOTE ]

heh

[spooky shadows]

iz 4 cowards

[john voight]

how would u lose money in the long run?
what happens if you run it 48 times?

[john voight]

idk why i picked 48, i odnt think it is even possible.

u get my point though?

[cachews]

omg i am so sick of this stuff; running it twice has no effect at all on EV, it just lowers variance

i mean, over time you'll play like a million hands, each time running it once; if you always run it twice that's two million hands, and a million is basically the same thing as two million, you see?

say you win with probability p (ignore ties, because then it doesn't actually work)

if you run it once, you win pot*p and lose pot*(1-p)... if you run it twice you win (pot/2)*p and lose (pot/2)*(1-p), twice... so by commutatitivity, the sums are the same

[Proofrock]

One thing I've actually wondered about this, though. When you run it twice, you remove cards from the deck so the two runs aren't really identical. The side that lost the first run should typically have a better chance of winning the second one. I imagine the effect on EV is small, but I don't think it's identically zero.

[DJ Sensei]

dont run it twice against a fish/heavy tilter unless you don't have reserve money.

[Chaser8]

[ QUOTE ]
One thing I've actually wondered about this, though. When you run it twice, you remove cards from the deck so the two runs aren't really identical. The side that lost the first run should typically have a better chance of winning the second one. I imagine the effect on EV is small, but I don't think it's identically zero.

[/ QUOTE ]

That might be true, but the Hero isn't going to win it the first time everytime. If the Hero has 70% equity, he's going to lose the first run 30% of the time. In those 30% of times, the Hero is ALSO going to have "a better chance of winning the second one." It all balances out. The point is not to have [for example] 70% equity every time you run it. You will win 70% in the longrun, however, you will fluctuate more on your way to approaching that 70% if you run it only once as opposed to more than once.

Just think of running the exact same hole cards on the exact same board millions of times. Each time, the equity is going to be exactly the same.