Statistics and Probability Dictionary

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Dotplot

A dotplot is a type of graphic display used to compare frequency counts within categories or groups. As you might guess, a dotplot is made up of dots plotted on a graph. Here is how to interpret a dotplot.

  • Each dot can represent a single observation from a set of data, or a specified number of observations from a set of data.
  • The dots are stacked in a column over a category, so that the height of the column represents the relative or absolute frequency of observations in the category.

Here is an example to show what a dotplot looks like and how to interpret it. Suppose 30 first graders are asked to pick their favorite color. Their choices can be summarized in a dotplot, as shown below.

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Red Orange Yellow Green Blue Indigo Violet

Each dot represents one student, and the number of dots in a column represents the number of first graders who selected the color associated with that column. For example, Red was the most popular color (selected by 9 students), followed by Blue (selected by 7 students). Selected by only 1 student, Indigo was the least popular color.

See also:   AP Statistics Tutorial: Dotplots