A box plot, also known as a box and whisker plot, is a type of chart that depicts a group of numerical data through their quartiles³. A box plot shows the distribution shape, central value, and variability of the data¹.

A box plot consists of the following parts:

• Minimum: The minimum value in the given dataset, excluding the outliers¹.

• First Quartile (Q1): The median of the lower half of the data set, or the 25th percentile¹.

• Median (Q2): The middle value of the data set, or the 50th percentile¹.

• Third Quartile (Q3): The median of the upper half of the data set, or the 75th percentile¹.

• Maximum: The maximum value in the given dataset, excluding the outliers¹.

• Box: The rectangle that contains the first, second, and third quartiles, representing the interquartile range (IQR) or the middle 50% of the data².

• Whiskers: The lines that extend from the box to the minimum and maximum values, indicating the variability outside the IQR².

• Outliers: The individual points that are beyond the whiskers, indicating extreme values that differ significantly from the rest of the dataset².

Here is an example of a box plot:

To create a box plot, you need to follow these steps:

• Sort the data in ascending order.

• Find the minimum, maximum, median, first quartile, and third quartile values.

• Draw a number line that covers the range of the data.

• Draw a box with its ends at Q1 and Q3, and draw a vertical line inside the box at Q2.

• Draw whiskers from the ends of the box to the minimum and maximum values, or to a specified distance from the box (usually 1.5 times the IQR).

• Plot any outliers as individual points beyond the whiskers.