Normal distribution
probability distribution / From Wikipedia, the free encyclopedia
The normal distribution is a probability distribution. It is also called Gaussian distribution because it was first discovered by Carl Friedrich Gauss.
The normal distribution is very important in many fields because many things take this form.[1] It is often called the bell curve, because the graph of its probability density looks like a bell.
- The mean ("average") of the distribution defines its location.
- The standard deviation ("variability") defines the scale.
These two parameters are represented by the symbols and , respectively.[2]
The standard normal distribution (also known as the Z distribution) is the normal distribution with a mean of zero and a standard deviation of one (the green curves in the plots to the right).[2]
Many values follow a normal distribution.[3][4] Some examples include:[5]
- Height
- Test scores
- Measurement errors
- Light intensity as in laser light)
- Intelligence is normally distributed.
- Insurance companies use normal distributions to model certain average cases.