Is Online Poker Rigged?

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Is Online Poker Rigged?

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Bad Beat Tests - Pre-flop All-ins - Explanation

Bad Beat Test

One common theory of how online poker could be rigged is the 'Bad Beat Theory'. In 'bad beat theory' good players receive more 'bad beats' than they should and poor players 'get lucky' too often when all the chips go in.

It has been argued that a site rigged in this way could increase its profit because the 'fish' would lose their money less quickly, the 'sharks' would win more slowly and therefore cash-out less often.

In this experiment we put some major online poker sites and networks to the test by analysing millions of hands to see if good players receive more 'bad beats' than they should...


Hypotheses

Null Hypothesis: Each online poker site is fair. The cards are dealt randomly.

Alternate Hypothesis: Each online poker site is rigged. The community cards are biased to favour losing players in 'pre-flop all-in' situations.

Explanation

In this test we anlaysed the results of 'heads up, pre-flop all-in' hands, i.e. hands in which exactly 2 players were 'all-in' before the flop.

We compared the 'Expected number of hands won' with the 'Actual Number of hands won' over a large sample size.

If our null hypothesis was true (i.e. each online poker site is fair):

The 'Expected number of hands won' would have been very close to the 'Actual number of hands won' for a large sample of hands.

Since we wished to compare results for winning and losing players it was necessary to make some assumptions:

Assumption1: good players more often than not get 'their chips in ahead', i.e. their hands will (on average) have an 'Expected Equity' of greater than 50%. Also, poor players more often than not get 'their chips in bad', i.e. their hands will (on average) have an 'Expected Equity' of less than 50%.

Assumption2: a good player's hand will more often than not 'dominate' their opponent's hand than vice-versa in pre-flop all-ins, i.e. their hands will have an 'Expected Equity' of between 68% and 83% more often than they will have an 'Expected Equity' of between 17% and 32%. For more information on 'dominated hands' click here.

If our alternate hypothesis and assumptions were correct (i.e. a poker site was rigged in this way):

1) Hands that are the favourite to win in an all-in situation would win less often than they should. Therefore the actual number of hands won would be fewer than the expected number of hands won for hands with an 'Expected Equity' of greater than 50%. The same applies to dominating hands.

2) Hands that were the underdog to win in all-in situations would win more often than they should. Therefore the actual number of hands won would be greater than the expected number of hands won for hands with an 'Expected Equity' of less than 50%. The same applies to dominated hands.

More information on these bad beat tests can be found on the Explanation, Dataset, Method, Results, Conclusions & Discussion pages.