http://www.ck12.org Chapter 5. Normal Distribution
areas on either side showing less wear. On average, people are more likely to have grabbed the handle in the same
spot and less likely to use the extremes on either side.
All of these examples show a typical pattern that seems to be a part of many real life phenomena. In statistics,
because this pattern is so pervasive, it seems to fit to call it “normal”, or more formally thenormal distribution.
The normal distribution is an extremely important concept because it occurs so often in the data we collect from
the natural world, as well as many of the more theoretical ideas that are the foundation of statistics. This chapter
explores the details of the normal distribution.
5.2 The Density Curve of the Normal Distribution
Shape
If you think of graphing data from each of the examples in the introduction, the distributions from each of these
situations would be mound-shaped and mostly symmetric. Anormal distributionis aperfectlysymmetric, mound-
shaped distribution. It is commonly referred to the as a normal, or bell curve.