Cheating scandal in chess: the field of statistics (

Hans Niemann (right) defeated world champion Magnus Carlsen from Norway in St. Louis with seemingly no effort.

Photo: dpa

The sport of chess is finally stuck in what is probably the biggest cheating scandal in its history. The focus is on the 19-year-old aspiring grandmaster Hans Niemann from the USA. Norway’s world champion Magnus Carlsen has repeatedly accused his opponent of using the forbidden help of computers in games in recent weeks. Since then, hardly anything else has been talked about in the various chess forums. A new level was finally reached on Tuesday, when leading chess platform published a 72-page report on why it banned Niemann for the second time just over a month ago.

Niemann is said to have cheated in more than 100 online games. The American had only admitted to using chess calculators on a few occasions as a 12- and 16-year-old, but never in tournaments with prize money. However, according to the report, in 2020 he was still cheating at 17, even in tournaments where thousands of dollars were at stake for the winners.

So far, Niemann has never been caught in the act, which is why observers tended to criticize world champion Carlsen for discrediting a young player without evidence. But it is now clear that Niemann himself lied to an important extent in his most recent public confession. This, in turn, lends more credence to Carlsen’s statement – “I believe that Niemann cheated more than he publicly admitted.”

At the beginning of September, the world champion left the prestigious Sinquefield Cup in St. Louis prematurely after losing to Niemann. He accused his opponent of playing winning moves too quickly and apparently effortlessly for a human in critical situations. Since Carlsen himself had played unusually poorly, many experts remained skeptical. The report also stated: “We found no direct evidence that Hans cheated in the game against Magnus or in other OTB games.”

OTB stands for “over the board”, i.e. on the real board instead of in online chess. This distinction is often made in the scene, since cheating is easier to accomplish online: the best computer moves can be displayed in a second browser window parallel to the game, without the opponent on the other side of the world finding out about it. On the other hand, there have been attempts to cheat on the board, but more sophisticated methods are required here. So far, the following have been discovered: hidden mobile phones in the toilet, small devices in shoes or hand signals from accomplices in the auditorium.

Fraud is much more difficult to prove online, although the sums involved have long been higher than in the few lucrative tournaments on the wooden boards. It is all the more important that portals such as use effective anti-fraud methods. This includes statistical algorithms that compare every move in a game with those of the computer programs.

If there are irregularities, lets experienced grandmasters compare the moves with the suspects’ past performances and with those of similarly strong players like Alireza Firouzja. The time required to discover complicated sequences of moves also plays a role. It is even recorded whether a player plays better or worse if he has other browser windows open at the same time or if he looks at another screen several times while streaming his games and then finds better moves.

In short: it’s complicated. But boasts of having caught several top 100 players cheating. They would have admitted that in private correspondence. As the report makes clear, the culprits then get off lightly: Niemann and others were simply given new accounts with which they were only not allowed to participate in monetary tournaments for a year. The public never found out about the allegations and confessions, after all didn’t want to lose the good players permanently.

A good 20 years ago, the world cycling association acted in a very similar way with prominent doping offenders. Positive tests such as those by Lance Armstrong were swept under the rug and witnesses were silenced. Later, even presidents of the UCI stumbled over this. That shouldn’t happen to the management of, because they don’t represent a federation, but a private company. And they now have a near-monopoly on online chess for amateurs and tournaments for professionals – now that Magnus Carlsen is also playing on

Nevertheless, dealing with cheaters is likely to change now, after all the chess world is in turmoil. And the affair is far from over, because Niemann is also accused of cheating on the board. Ever since Carlsen made the first suggestions in St. Louis, statisticians and engineers have excelled in finding evidence and means of fraud. The French player Yosha Iglesias presented calculations according to which Niemann unusually often played games in which every move corresponded to that of a computer. Allegedly, ten of these perfect games can be found in the databases, plus 23 with an accuracy of more than 90 percent compared to the computer. Carlsen, by far the best player of this generation, has only ever played two games with 100 or at least over 90 percent accuracy.

The Brazilian data analyst Rafael Milk followed suit: According to him, all top players develop gradually on the way to a higher playing level: This means that their moves are initially far removed from those of the computer on average, but become more similar over the years with more experience and training but more and more. In addition, the rashes, i.e. games in which they play particularly well or badly, are becoming less frequent. Milk demonstrated this apparently natural development for countless top players, including Carlsen and the German Vincent Keymer.

Niemann, on the other hand, made an unusual leap when he reached a score of 2500 in the standard Elo rating system. Elo generally describes the playing strength of chess players, Magnus Carlsen currently has the highest at 2853. He needed four years for the 200 points before that, he managed the next 180 in just 18 months. Although the American has now reached a rating of 2699, he still makes far more mistakes compared to other players of his strength, according to Milk. So the rashes mentioned above don’t match his numerical playing strength. So the chess world is asking: How did Niemann get this Elo rating? How could he defeat so many other grandmasters at this level? “My calculations are strong evidence that Hans Niemann cheated,” is at least Milk’s clear answer to this question.

But how did he do it? Tournament organizers have long checked the toilets for hidden cell phones. The opponents are scanned with metal detectors to detect devices on the body. So various YouTubers tinkered with programmed devices to swallow, and even Elon Musk mentioned on Twitter a previously rather funny theory of anal beads that could secretly send a signal via vibrations to a player which move would be the best. The chess scandal even found its way onto the biggest comedy talk shows on US television.

Although only has great expertise in the field of online cheating, the platform now also dared to analyze Niemann’s performance at the board. According to one verdict, Yosha Iglesias’ methodology does not meet its own standards. According to his own calculations, Niemann even played perfect less often than comparable talents.

A big problem anyway is that top players don’t have to play perfectly. One or two computer moves at the right time are enough to decide a game. So it wouldn’t be necessary for Niemann to play a 100% accurate game either. This in turn makes it even more difficult to distinguish scammers from honest players. After all, a flash of inspiration here and there can happen to anyone.

Nevertheless, the analysts at also write that Niemann’s rise over the past two years is “statistically extraordinary”. “While their performances in some matches are within the realm of statistical possibility, the likelihood of a player performing that well over such a long period of time is incredibly slim,” it says. In addition, the leap in quality that Niemann made between the ages of 11 and 19 even surpassed that of Bobby Fisher and Magnus Carlsen, who chess experts worldwide rank among the three best players in chess history alongside the Russian Garry Kasparov.

Niemann says he simply put a lot more time into training after his suspension from in 2020 to prove to himself and the world that he is one of the greats of the scene. And unless he’s caught right at the board with a hidden mini-computer, there’s still the slightest possibility that he’s simply the greatest chess genius the world has ever seen. But now only he can really believe in it.



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