Normal Distribution
The normal distribution is a bell-shaped continuous probability distribution that is parameterized to a mean and standard deviation.
Description
The distribution is bell-shaped.
- 68.27% of the cumulative distribution is within 1 standard deviation of the mean
- 95.45% within 2
- 99.73% within 3
Statistics
The mean and standard deviation are necessarily given by the distribution formulation.
Usage
Standard Normal Distribution
The normal distribution characterized by a mean of 0 and a standard deviation of 1 is called the standard normal distribution. This distribution is referenced for Z scores (alternatively called Z statistics).
As an example, for a two-tailed test and a significance level of 5%, the critical Z score value is 1.96.