Party Poker Player Bias

[MyNameIsMud]

Ok I know what everyone is thinking, another Party is rigged post. That may be true but this is different, please read the whole post before flaming me.

background:
I have been playing online poker for some time now and have long been a winning player. I have been playing mostly 100NLHE on party, and latley on poker stars.

I had a very good win rate for many months, then I noticed a sudden drop in my winrate at party poker.

Try as I might I could not find leaks to explain it, all I kept seeing was that I was no longer making much money with premium hands, I have been struggling with this for some time now, and finally found something worrysome.

I have 33,229 hands in PT since mid may (when I lost all my data). I went through the stats on the hands that have historically made me money and this is what I found:


These are based on hands where a flop was dealt, regardless of wether or not I was still in the hand, and applies to 3 FLOP cards only.

Made a pair on the flop (expected 36.7%)


Flops - Hits - %
AKx
261 - 79 - 30.2% (-6.5%)

AQx
286 - 107 - 37.4% (+0.8%)

Total - 34%, an 11% shortfall, 20% for AK.

I was willing to accept the above, but this I cannot:

Hit set on flop:
Hand - Flops - Hits - %
AA - 104 - 7 - 6.7%
KK - 98 - 9 - 9.2%
QQ - 119 - 12 - 10.1%
JJ - 109 - 7 - 6.4%
TT - 115 - 15 - 13%
99 - 146 - 11 - 7.5%
88 - 170 - 17 - 10%
77 - 139 - 15 - 10.7%
66 - 138 - 13 - 9.4%
55 - 122 - 12 - 9.8%
44 - 143 - 13 - 9.1%
33 - 134 - 20 - 14.9%
22 - 138 - 17 - 12.3%
TOTAL- 1675 - 168 - 10.029%
Expected - 204

That is a 17.6% shortfall.

One more, just for fun:

KK saw flop 93 times, 29 times an A flops (31.1%, expected 24.4%) About 33% more than axpected.


Seems as if the deck is stacked against me. How can this be explained? Please, tell me there isnt realy 52 cards in the deck, or this is actually within the realm of probability.

What realy chaps my ass is that I have still won a fair amount over these 33K hands, so I can still beat the game even with these numbers, and I don't want to quit partypoker.

33 THOUSAND hands. I am mystified. Is 33,229 hands not a rational sample size?

BTW my winrate at pokerstars is what it used to be at Party. [img]/images/graemlins/tongue.gif[/img] so as Winston ChurchHill used to say, "Bugger them all!"

Ok let me have it.

-MyNameIsMud

[El Barto]

Your "expected" number of times to complete a set, and times an A flops vs. KK appears too high by my calculations.

[MyNameIsMud]

Flop a set (or quads) 2/50 + 2/49 + 2/48 = 6/49 = 12.24%
12.24% of 1675 = 204.3

No?



At least 1 A on flop (no A in hand) 4/50 + 4/49 + 4/48 = 12/49 = 24.48% ??

24.4% of 93 = 21.8

??

[El Barto]

your calculations ignore the posibility of flopping quads (vs PP) or 2 or 3 As on the flop (vs KK). You need to look at odds for "set or better".

2/50 + (2/49 * 48/50) + (2/48 * 48/50 * 47/49)

[MyNameIsMud]

I was calculating the chances of hitting a two outer with 3 cards dealt, hitting at least one out.

I admit I do not have a background in math, but I fail to see how your point makes any difference, it changes the expected numbers only slightly.

or are you trying to tell me that the true odds of flopping a set or better are in fact 10:1 ??

Because that is what happened, and that is the point.

[El Barto]

my point is 204 minus 168 is only 36 (and the correct number is smaller)

Is it that hard to believe that things go wrong for you a few dozen times versus expected? (we all know about very long downswings afterall).

why don't you post results with other hands (like all suited broadways). I bet some "hit well" quite more than "expected".

I notice your 22 and 33 perform quite well [img]/images/graemlins/grin.gif[/img]

[MyNameIsMud]

That is basically the point of posting this, I do understand downswings, but this honestly seems to go too far, 36/204 is a huge number after 1675 flops, 16%, and I just have trouble believing it. 15-25% shortfall across the board, from AK to 22, after 33K hands.

Can you point me to some standard deviation calculations? I would like to know the actual chances of this sort of deviation.

[El Barto]

If you really want to dig into the numbers, post this in the Probability forum - there are some true geniuses there. I can't help much.

[El Barto]

Another thought, you said that this is based on hands that go to a flop. When you have a high pair and you raise, mostly people with good hands will call you - which may reduce your outs when you see the flop.

If you raise AA, you are more likely to see the flop if someone has an A in their hand, but this reduces the likelihood of an A hitting the flop. So you can't expect to hit the mathematical number in the long term. The never dealt flops would have hit your set more often.

[1800GAMBLER]

Sklansky shows how you can work out if you are being 'cheated' in one of his Gambling books by using Bayes Theorm, post this in the probability forum and see what they make of it.