The Normal Distribution

A. The Normal Distribution

Frequency distributions represented in the form of histograms can take on a variety of shapes. One shape that commonly occurs, and is important in the study of statistics, is the normal distribution. This distribution is sometimes called the Gaussian distribution or the bell distribution. When data is normally distributed, the mean, median, and mode all have the same value. In a normal distribution, the data is symmetrical about the mean and the shape of the histogram representing the data is that of a bell. Nearly all of normally distributed data lies within three standard deviations of the mean.

Distributions that are Normal

Distributions that are not Normal

The coin toss experiment you performed in the Warm Up represents a normal distribution. You likely discovered that the more trials you ran (the more you tossed the coins), the closer to normal the data became.

Many real world data sets are approximately normal. Understanding the normal distribution can help you interpret those data sets.