normal distribution

A curve used in statistics to represent the distribution of data which is symmetrical about its mean value.

In statistics, a distribution widely used to model variation in a set of data which is symmetrical about its mean value. It can be expressed in the form:

where f(x) is the relative frequency of data value x, ςis the standard deviation, μ is the mean, exp is the exponential function, and π is a mathematical constant. The curve resulting when f(x) is plotted against x is called the normal distribution curve.

An example of normal distribution can be found in the intelligence quotients (IQs) found in human populations, distributed around a mean value of 100. The distribution is also known as the Gaussian distribution after German mathematician Karl Gauss.