Detecting an online poker cheat

Question

It recently emerged on a large poker site that some players were possibly able to see all opponents cards as they played through exploiting a security vulnerability that was discovered.

A naïve cheater would win at an incredibly fast rate, and these cheats are caught very quickly usually, and if not caught quickly they are easy to detect through a quick scan through their hand histories.

The more difficult problem occurs when the cheater exhibits intelligence, bluffing in spots they are bound to be called in, calling river bets with the worst hands, the basic premise is that they lose pots on purpose to disguise their ability to see other players cards, and they win at a reasonably realistic rate.

Given:

• A data set of millions of verified and complete information hand histories
• Theoretical unlimited computer power
• Assume the game No Limit Hold'em, although suggestions on Omaha or limit poker may be beneficial

How could we reasonably accurately classify these cheaters? The original 2+2 thread appeals for ideas, and I thought that the SO community might have some useful suggestions.

It's an interesting problem also because it is current, and has real application in bettering the world if someone finds a creative solution, as there is a good chance genuine players will have funds refunded to them when identified cheaters are discovered.

Answer 1

Plot V$PIP versus winrate of all players with a statistically significant #hands played. You should see outliers with naked eye. I think that's the basic thing to do first.

Then you can plot WTSD vs winrate, winrate at showdown vs winrate without showdown, %won at showdown vs VPIP.

The stats you choose must be significant statistically. If you know poker, the above choices make sense.

This is not a job for a machine, outliers are detected by eye.

EDIT: Omaha is much tougher, since it is really variant. There are cases of unbelievable streaks made by weak players who were not cheating.