Box Plot

This is a box plot, or a box and whisker plot.  In this case, the data being measured is the essay scores of a control group, and an experimental group.  The boxes show where most of the data falls.  For example, the blue box in the Ed tech Science category shows that most test takers in the control group scored between 1.00 and 3.00 with 2.00 being most common.  The outlier data, or whiskers show that although the majority scored between 1.00 and 3.00, some test takers scored as low as 0.00, and as high as 5.00.  Therefore, a box plot is a useful visual tool to display a data set.
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