Does momentum and a "hot hand" exist? Scientists determined they don't – and then came the twist
Do basketball players have a higher chance of scoring the more they have scored before? Researchers tried to prove they don't – until other researchers arrived and discovered a significant flaw in the research method.
If you have ever watched a basketball game, you have probably heard the phrase "this team has momentum" at least once. Three baskets in a row, the crowd is in a frenzy, the opposing coach calls a timeout — and suddenly it seems like the run cannot be stopped. But does momentum really exist, or is it just a feeling?
This is a question that has occupied sports researchers for decades. On one hand, players, coaches, and fans swear they can feel when a player has "entered the zone." On the other hand, statistics have spent years trying to prove that this whole story is mostly an illusion.
It all started in 1985, when three researchers, including the Israeli psychologist Amos Tversky, published a study that became one of the most famous in the field. They examined what is known as the "hot hand" — the idea that after several successful shots, a player's chance of scoring again increases. Their conclusion was surprising: even if a player made three shots in a row, the chance of them making the next one barely changes. From their perspective, the hot hand was mainly an illusion stemming from the human tendency to find patterns even when they do not actually exist.
This study influenced the world of psychology, economics, and sports for nearly three decades. It became a classic example of how our brain loves to see sequences and attribute meaning to them, even when they can be created entirely by chance.
But then came the twist.
In 2015, two statisticians, Joshua Miller and Adam Sanjurjo, returned to that exact same study and discovered a surprising problem: they did not claim the data was wrong, but that the way it was analyzed was biased from the start.
To understand the error, they used the example of a coin toss. If you toss a coin fairly, it is clear that the chance of getting heads after heads is still 50%. But when looking back at short sequences and calculating what happened after every time heads came up, a mathematical bias is created that causes the average result to be lower than 50%, even though the coin is completely fair.
The reason for this is that when a result comes up that breaks the sequence, such as a miss after a make, it also ends the possibility of continuing to check the sequence. Conversely, another make both extends the sequence and creates another opportunity to enter the calculation. This structure creates a built-in bias against finding a "hot hand."
In simple terms, even if there is no change in a player's ability, the old calculation method could make it look as if they are actually shooting worse after a streak of shots.
When Miller and Sanjurjo corrected the method and re-analyzed the same data, the picture changed: suddenly, evidence appeared that the hot hand actually exists. This is not a radical change, where a player instantly becomes an unstoppable shooter, but a small yet real increase in the probability of scoring after a successful streak.
