Math 225 Course Notes

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Chapter 2


Big Picture

Data from a single variable is best summarized by a graph. You will learn how to make and interpret histograms and stem-and-leaf displays. Graphs also help to identify unusual observations or outliers. The distribution of each variable is described by summarizing its center, spread, and shape. The two most important numerical summaries of center are the mean and the median. The most important numerical summary of spread is the standard deviation. The variance is simply the square of the standard deviation. The shape of a graph may frequently be described as being symmetric or skewed to the left or right. It may be bell-shaped, or perhaps bimodal.

Last modified: Jan 15, 1996

Bret Larget,