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Distributions
by David M. Lane and Heidi Ziemer

Prerequisites
• Chapter 1: Variables

Learning Objectives

  1. Define “distribution”
  2. Interpret a frequency distribution
  3. Distinguish between a frequency distribution and a probability distribution
  4. Construct a grouped frequency distribution for a continuous variable
  5. Identify the skew of a distribution
  6. Identify bimodal, leptokurtic, and platykurtic distributions

Distributions of Discrete Variables

I recently purchased a bag of Plain M&M's. The M&M's were in six different colors. A quick count showed that there were 55 M&M's: 17 brown, 18 red, 7 yellow, 7 green, 2 blue, and 4 orange. These counts are shown below in Table 1.

Table 1. Frequencies in the Bag of M&M's

This table is called a frequency table and it describes the distribution of M&M color frequencies. Not surprisingly, this kind of distribution is called a frequency distribution. Often a frequency distribution is shown graphically as in Figure 1.

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