• Entry
• Entries A-Z
• Subject index

### Normal Curve Distribution

Normal curve distribution is a symmetrical distribution, which has a bell shape and identical scores for the mean (i.e., the average score), median (i.e., the middle score splitting the bottom 50% from the top 50% in the distribution), and mode (i.e., most frequent value). A bell-shaped curve (see an example in Figure 1) characterizing the normal distribution can be represented by the equation below:

$\mathrm{Y}=\frac{N}{\sqrt{2\pi \sigma }}e-\frac{{\left(\mathrm{X}-\mu \right)}^{2}}{2{\sigma }^{2}}$

where Y = frequency of a given value of X; X = any score in ...