Statistical Consultants Ltd
The Galton Box
History of Statistics, History of Science and Technology
The Galton Box (also known as a bean machine or quincunx), was invented by Sir Francis Galton in the 19th century. Its purpose is to demonstrate the central limit theorem and the binomial and normal distributions.
As a ball falls, it will bounce either left or right when it hits a pin. If there are N rows of pins, then the ball would bounce N times. The position of the bin the ball falls in, would have a binomial distribution where:
If the number of rows of pins is large enough, this would approximate a normal distribution due to the central limit theorem.
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