How to Create a Box & Whisker Graph

Creating a Box and Whisker graph is easy and can help summarize your data.

According to the CSDSAC Math Glossary, a box and whisker graph is "a graphic method for showing a summary of data using median, quartiles and extremes of data. A box plot shows where the data are spread out and where they are concentrated." Creating a box and whisker graph is very easy if you understand how to set up the quartiles correctly.

Things You'll Need

• Piece of paper
• Pencil
• Collection of number data
• Calculator

Instructions

1. Arrange all of your data numbers in order. Find and circle the middle number. This number is the median. If the set of numbers is an even number, take the two middle numbers, add them, and divide them by two to find the median. Use a calculator if necessary.

2. Get the median of the lower set of numbers (every number below the original median) as well as the the median of the higher set of numbers (every number above the original median.)

3. Create a number line on a piece of paper using a pencil. Let the number line begin with your lowest data number and end with your highest. The first and last numbers will be known as the lower and upper extremes.

4. Mark the three medians on the number line. Draw a box that extends from the first median to the last, leaving the original median somewhere inside the box.

5. Add the whiskers, or lines that extend from the ends of the box to the corresponding extreme. In other words, one whisker will come out of the right end of the box to the upper extreme, and the other will extend from the left end of the box to the lower extreme.

References

• Cedarville University: Making a Box and Whiskers
• Peltier Technical Services: Box and Whisker Plots
• CSDSAC Mathematics Standards Glossary

Resources

• Purple Math: Box-and-Whisker Plots: Quartiles, Boxes, and Whiskers