Box Plots (Box and Whisker Plots)

Box plots

A box plot is a graphical tool that lets you easily visually compare variation between the data sets evaluated. Also makes comparisons quickly and easily.

  1. Median.
  2. Maximum.
  3. Minimum
  4. First quartile (0-25%)
  5. Third quartile (75%)

What Can Box Plots Tell Us?

  • Skewness: By looking at a box plot you can can tell if your data distribution is skewed if the line inside the box is not centered.
    • Ex. Stock 4’s median is not centered, thus this data is skewed.
  • Extreme values: The vertical lines (whiskers) show max and min values.
    • Ex. Stock 5 tends towards larger values.
  • Median: The blue horizontal line indicates the median of the group.
  • 25th & 75th Percentiles: that’s the top and bottom of the box.
    • Useful in visualizing most of the spread of variation.
    • Ex. Stock 1 typically has the least variation.


Creating a Box Plot

Good article on how to do this in excel.

Notes on Box Plots

Box Plots, Histograms, and Stem and Leaf plots all display the same data.



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