Normal Distribution

The normal distribution, which is also called a Gaussian distribution, bell curve, or normal curve, is commonly known for its bell shape (see [Page 927]Figure 1) and is defined by a mathematical formula. It is a member of families of distributions such as exponential, monotone likelihood ratio, Pearson, stable, and symmetric power. Many biological, physical, and psychological measurements, as well as measurement errors, are thought to approximate normal distributions. It is one of the most broadly used distributions to describe continuous variables.

Figure 1 The Normal Distribution

The normal curve has played an essential role in statistics. Consequently, research and theory have grown and evolved because of the properties of the normal curve. This entry first describes the characteristics of the normal distribution, followed by a discussion ...