Sampling and bias

Ages 13 to 17 Read alone · about 35 minutes

Read together

A sample is a small group used to learn about a bigger group. It must be chosen fairly, or the results mislead.

A random sample gives everyone a chance to be picked.

Do it

1. Choose a question, such as how many hours classmates or friends sleep.
2. Collect data first from only your closest friends, then from a random draw of names from a hat.
3. Compare the averages. Which is likely closer to the whole group?
4. Write one sentence on what could bias a survey.

Talk about it

• Who was left out?
• How could the question wording change answers?

For the grown-up

Understanding sampling helps teens read polls and claims in the news critically. Surveys of peers should be anonymous and respectful.

Mark as done

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Where this comes from

• National Governors Association Center for Best Practices and Council of Chief State School Officers, Common Core State Standards for Mathematics (2010), standard 7.SP.A (random sampling to draw inferences)
• Freedman, D., Pisani, R., and Purves, R., Statistics (W. W. Norton, 4th edition, 2007)

Written with AI assistance and checked against the sources listed. Please read it before sharing it with a child.