Dot Plots

Example

Suppose 30 first graders are asked to pick their favorite color. Their choices can be summarized in a dot plot, 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.

In this example, note that the category (color) is a categorical variable, so it is not appropriate to talk about the symmetry or skewness of this dot plot.