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5.7:

Boxplot

JoVE Core
Statistics
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JoVE Core Statistics
Boxplot

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The boxplot, or box-and-whisker diagram, is a visual representation of a 5-number summary. The boxplot shows the minimum value, first quartile, second quartile, third quartile, and maximum value. It also provides information about the spread of the data as well as the outliers.

Consider the top ten goal scorers from the World Cup matches.

To construct the boxplot, first, sort the number of goals from low to high, and find the 5-number summary.

Create the boxplot by drawing a rectangle box extending from quartile one to quartile three, followed by a line through the box at the second quartile, and a line connecting the minimum and maximum values.

Boxplots of normal distributions typically show the median at the center of each box, while in a skewed distribution, the median moves either forward or backward.

Boxplots are often helpful in comparing two or more different data sets. For instance, comparing the number of goals scored by the champion team in the two world cup match series would reveal how the team's performance changed over time.

5.7:

Boxplot

Box plots (also called box-and-whisker plots or box-whisker plots) give an excellent graphical image of the concentration of the data. They also show how far the extreme values are from most data. A box plot is constructed from five values: the minimum value, the first quartile, the median, the third quartile, and the maximum value. We use these values to compare how close other data values are to them. To construct a box plot, use a horizontal or vertical number line and a rectangular box. The smallest and largest data values label the endpoints of the axis. The first quartile marks one end of the box, and the third quartile marks the other end of the box. Approximately the middle 50 percent of the data falls inside the box. The "whiskers" extend from the ends of the box to the smallest and largest data values. The median or second quartile can be between the first and third quartiles, or it can be one, the other, or both. The box plot gives a good, quick picture of the data.

This text is adapted from Openstax, Introductory Statistics, Section 2.4 Box Plots