Galton Board

Infinity candle

The Galton Board is an ingenious math gadget, that demonstrates the most important distribution in all of statistics.

The Galton Board is named after its inventor Sir Francis Galton. The box contains thousands of tiny metal balls, and when you turn the board, they start falling through the pegs and scatter randomly. Once all the balls have fallen into the slots, they form a curve of the same shape almost every time. This curve is also plotted on a Galton box and is called a normal distribution curve or a Gaussian curve. The normal distribution is an approximation of the binomial distribution for a sufficiently large number of trials.

A ball bouncing off the peg and falling into a certain slot can be seen as a random event. The ball can bounce off the peg either to the left or right. It is more likely that it will have bounced roughly the same number of times to the right and left before reaching the slot and falling into the middle slot. The probability of a ball falling further to the left or the right is less likely because, for this, the ball has to make more bounces to the left or right, respectively.

A sufficiently large number of balls allows us to observe in the Galton box how seemingly random events can form a certain regular distribution every time. This makes a Galton Box a great math gadget that helps you visualize the most famous distribution in all of statistics.