Dot Plots and Stem-and-Leaf Plots

Key idea

Show the shape of small datasets.

In depth

These keep every data value visible while showing shape. A dot plot stacks dots over a number line; a stem-and-leaf plot splits each number into stem (leading digits) and leaf (last digit). Both make median and mode easy to find.

Worked example

Values 12, 15, 21, 23, 23: stems 1 | 2 5, stem 2 | 1 3 3. Key: 1|2 means 12.

Real-world uses

• Showing the shape of a small dataset such as ten test results at a glance

Common mistake

Forgetting the key, or not sorting the leaves.

How to learn this

1. Read the key idea and say it in your own words.
2. Work through the worked example, then try a similar problem.
3. Use the interactive lesson’s visual and mini-quiz to check the pattern.

Frequently asked questions

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Related intermediate topics in Probability & Statistics

• Collecting Data and Sampling – Surveys, experiments and random sampling.
• Bias in Sampling – Systematic errors that make samples unrepresentative.
• Histograms – Bars showing frequency of numerical intervals.
• Mean – The arithmetic average.
• Median – The middle value of an ordered list.
• Range – Difference between maximum and minimum.