Box and whisker charts, also known as box plots, are a type of graphical representation that display the distribution of a dataset. They are often used in statistics to visualize the spread of a dataset, including its median, quartiles, and outliers.
A box and whisker chart shows distribution of data into quartiles, highlighting the mean and outliers. The boxes may have lines extending vertically called “whiskers”. These lines indicate variability outside the upper and lower quartiles, and any point outside those lines or whiskers is considered an outlier.
The box in a box and whisker chart represents the interquartile range (IQR), which is the range between the first and third quartiles of the data. The line inside the box represents the median, which is the middle value of the dataset.
The whiskers, which extend from the box, represent the range of the data beyond the first and third quartiles. The length of the whiskers is typically set to 1.5 times the length of the IQR, and any data points that fall outside of this range are considered outliers and are plotted as individual points.
Box and whisker charts are particularly useful for comparing the distribution of multiple datasets side-by-side. By comparing the medians, quartiles, and range of each dataset, it is possible to quickly determine which datasets have a larger spread or more variability. Box plots can also be used to identify skewness or other features of the distribution of the data.