Are Some Roulette Wheels Biased?

Ever heard of Gonzalo Garcia-Pelayo? Probably not as a record producer, despite the fact that Gonzalo tried to make it in the music business. But Gonzalo was passionate about gambling, and roulette in particular. Although Gonzalo is something of a mathematician, it was his recourse to engineering that led him to believe that the average roulette wheel could not be completely and perfectly balanced, and that if one could find some kind of bias in the wheel’s operation, then one could increase the winning rate beyond the point of a consistent house profit on the table.  

Above: Gonzalo Garcia-Pelayo, Music Meister Or Gambler?

At the Casino de Madrid (yes, that’s in Madrid), Gonzalo found his imperfect wheel and ended up winning the €600,000 in a single day, and a total of €1 million before the casino picked him out and prevented him from playing any further. In statistical terms, Gonzalo’s observation of biased wheels meant that a game with an intended house edge of 5% was flipped into having a player edge of 15%.

Perhaps quite predictably, the Casino de Madrid was less than pleased with Gonzalo’s fortunes. The casino decided to sue him, alleging that his unnatural winnings constituted an instance of cheating, and could therefore not be deemed to be valid. We're happy to say that the court ruled in favour of the little guy: Gonzalo, the court said, didn't cheat, and the onus was on the casino to ensure that its facilities were in proper working order  – the casino should fix it wheel, they said.
Interestingly, this little piece of litigation only ended in 2004, so the case remains relatively fresh in the public consciousness.

Some serious prophylaxis required

As a result of cases like Gonzalo’s (and not a few before him: men like Joseph Jagger, for instance, who in the 19th century took the house for a couple of hundred thousand francs thanks to a faulty wheel), most modern-day casinos have become fairly paranoid about the accuracy and alignment of their roulette wheels. The Gonzalo case set something of a precedent for the way the courts approach the casino crying foul just because they found themselves losing, instead of made, money. Although not binding on international courts, the Gonzalo case is a rare instance of the house being hoisted by its own petard – that is, having its own, built-in mathematical advantages turned volte-face against it. Even today, none of Gonzalo’s family members are permitted to enter the Casino de Madrid, so deep is their suspicion of him in this family.

Stories like these are just one of the many reasons that modern gambling houses keep such precise and detailed records of player behavior, betting tendencies, psychological profiles and table habits. The house wants to know how you bet, where you bet, and why you bet, as it helps them build a more complete idea of the relative risk of having new in casino in the first place. Once you become too risky (which is really another way of saying, want to become too successful), expect be given marching orders. Take what you can, while you can.