A box-and-whisker plot shows the variability of a data set along a number line. It uses a rectangular box and two segments. These segments are called whiskers.
The box extends from the first to the third quartiles (Q_1 and Q_3), with a line in the middle indicating the median (Q_2) of the data.
The first quartile is the median of the lower half of the data and the third quartile is the median of the upper half of the data.
The first segment extends from the least value of the data to Q_1, while the second one extends from Q_3 to the greatest value of the data.
The set of numbers used to draw the box plot is called the five-number summary of the data set. Each of the five numbers is labeled accordingly.
Additionally, by only looking at the box-and-whisker plot, we can state some facts about the data set.
If the whiskers are approximately of the same size and the median is in the middle of the box, the data is symmetric.
If the left whisker is longer than the right whisker and most data are on the right, the data is skewed left.
If the right whisker is longer than the left whisker and most data are on the left, the data is skewed right.
Now, consider that the given box-and-whisker plot.
Notice that the whiskers are approximately of the same size, and the median is in the middle of the box. Therefore, the distribution is symmetric.
