Boxplot (Vertical)

Box Plot (Box-and-Whisker)

A box plot summarizes the distribution of a numerical variable using five key statistics: the minimum, first quartile (Q1), median, third quartile (Q3), and maximum. The box spans Q1 to Q3 (the interquartile range), a line marks the median, and whiskers extend to the data extremes, with dots marking outliers beyond a defined threshold.

• When to use it? 

  Box plots are essential when comparing the distribution of a numerical variable across multiple groups — for example, salary distributions by department, or test scores by school. They condense a full distribution into a compact, comparable form.

• What makes it effective? 

  In a single symbol, a box plot communicates central tendency (median), variability (box width), skewness (asymmetric box or whiskers), and the presence of outliers. This makes it far more informative than showing only a mean or bar.

• When to avoid it? 

  Box plots can be misleading when distributions are bimodal or complex, as the summary statistics hide the underlying shape. In such cases, combine with a violin plot or individual data points (strip plot) for a fuller picture.

Box plots are the standard tool for distribution comparison in statistical analysis and scientific communication.