Box and Whisker Plot (Boxplot)

A box and whisker plot, commonly referred to as a boxplot, is a statistical chart used to summarize and display the distribution of a dataset. It provides key insights into the data’s spread, central tendency, and potential outliers. Here’s a basic breakdown of its components and how to interpret them.

1. Box:  The central rectangle represents the Interquartile Range (IQR), which contains the middle 50% of the data.
   • Lower edge (Q1):  The 25th percentile, or the first quartile.
   • Upper edge (Q3):  The 75th percentile, or the third quartile.
2. Line inside the box (Median):  The line inside the box shows the median (50th percentile) of the data, which divides the data into two equal halves.
3. Whiskers:  The lines extending from the box indicate the range of the data within 1.5 times the IQR from the lower and upper quartiles.  Whiskers show the minimum and maximum values that are not considered outliers.
4. Outliers:  Data points that lie beyond the whiskers are marked as individual points. These are potential outliers that deviate significantly from the rest of the data.

Below is an illustration showing the different components of a Boxplot:

Here is another illustration with some real numbers displayed: