Interesting concept I just learned. I thought I'd relay some of the information.

Showdown Bias - If we only see showdowns when Hero calls Villain's bet. Then it will appear that the bettor is bluffing more than he actually is. This is because the caller's range will have a disproportionate amount of removal on the bettor's value hands when compared to the bettor's bluffs.

Example:

Assume your opponent bets 2/3 OTR with a perfectly polarized and balanced range of 71% Flushes and 29% Bluffs.

Now let's assume our calling range consists of 75% Flushes and 25% sets. What is the effect of showdown bias in this example?

Since there are 3 cards to a flush on the board (13 in the deck) - there are 10 flush cards remaining (choose 2), which equals 45 combinations of flushes.

But if we have a flush - that means we remove 2 cards that our opponent could of used to make a flush. So now there are only 8 flush cards remaining (choose 2) or 28 combos.

That means we subtracted 17 combos (45-17 = 28) or 38% of removal of his flushes.

Our sets (25% of our range) will have a very small removal effect of around 5% of our opponent's flushes because sets will sometimes hold one card that can make a flush around 25% of the time.

So if we call with 75% flushes and 25% sets, we will have a 38% removal on the opponent's value range 75% of the time and a 5% value range removal the other 5% of the time.

That means our weighted average of removal is .75*.38 + .25*.05 = 30%.

So when we call, it will not appear as if our opponent bet a balanced range of 71% Flushes and 29% Bluffs.

It will appear as if he bet around 50 combinations of value 71*(1-.30) and 29 combinations of bluffs

Our value will also have some removal on Villain's bluffs, but it will be a small factor.

So in this hand example, it appears Villain's value betting range is 50 combos and his bluffs are 29 combos (50/79 = 63%). So his value betting range is only 63% - when in reality it is 71%.

Therefore the effect of Showdown Bias is 8%

Maybe you guys have heard of this before but it was news to me, hope you enjoyed it.

Interesting idea. I'm not so sure that blockers on bluffing range are negligible. You often should bluff with hands that block strong hands and bluff range is smaller so effect are bigger.
If without blockers V is betting 100combos 67 value and 33 bluff if your hand blocks one of each. Then you'll see less bluffs not more(66/98=67.3% value).

k

I think it has to do with the specific cards too. So let's say we had Tc9c and there's 3 clubs on the board. Well how often is Villain going to use a Tc or 9c to bluff? Probably not very often.

So we always block the flushes but we don't always block the bluffs.

So if I understand this basic idea correctly: we will call bets vs villains more often with blockers to their value range, so they will have these hands less often in terms of a % of their overall range, and as such, we incorrectly believe villain's overall range will be slightly more weighted towards bluffs?

idk about all that math **** tho, I'm not a numbers guy b

Yeah I'm not really a number guys either but it's just combos/bluffing frequencies so nothing too crazy.

Yeah that's right. We incorrectly believe Villain's bluff more than they actually do by nature of our calling range.

Very interesting observation, Doodoo.

Yeah it makes sense that value hands block other value hands, and therefore when you call with a value hand you'd be more likely to see a bluff.

Conversely, you're more likely to be called when bluffing than when value betting, as your value bets tend to block more calls.

Another example is that you're less likely to see a flop with AA as you block more of people's continuance range.

I think it's a fair generalization to say that value hands are more likely to block value hands than bluffs.

Thanks. I can't take credit for the idea though. But I do think it is pretty relevant when thinking about bluffing/bluff catching.

What you said also makes sense. We are more likely to called when bluffing than when we have value.

ty

Very cool topic DooDoo.

With the range clairvoyance of Ignition, we should have zero guesses as to the value/bluff and everything in between (razor thin value and merged betting with 3rd pair). I think for guys playing in pools where mucked cards aren't seen, this is a good way to think about things in general.

Good point. It doesn't matter on Ignition but Other sites/live poker it will be relevant.