Lesson 3: Biased Data

About 30 minutes — Discussion-based lesson

What You Will Learn

This lesson covers:

What bias means: a built-in unfairness that skews results
Selection bias: who you chose to ask
Question bias: how you worded the question
Confirmation bias: only seeing data that supports what you already believe

What bias means: a built-in unfairness that skews results

This section covers the key ideas about what bias means: a built-in unfairness that skews results. Discuss with your group or family and explore the concepts together.

Selection bias: who you chose to ask

This section covers the key ideas about selection bias: who you chose to ask. Discuss with your group or family and explore the concepts together.

Question bias: how you worded the question

This section covers the key ideas about question bias: how you worded the question. Discuss with your group or family and explore the concepts together.

Confirmation bias: only seeing data that supports what you already believe

This section covers the key ideas about confirmation bias: only seeing data that supports what you already believe. Discuss with your group or family and explore the concepts together.

Check Your Understanding

1. What is bias in data?

Answer: Bias is a built-in unfairness that pushes results in one direction. It can come from who you ask, how you ask, or how you interpret the results.

2. What is selection bias?

Answer: When the people you surveyed are not representative of the whole group. Surveying only athletes about favorite activities will bias results toward sports.

3. What is confirmation bias?

Answer: Paying attention to data that supports what you already believe and ignoring data that contradicts it. Everyone does this — being aware of it helps you fight it.

4. How can you reduce bias in your data?

Answer: Ask a representative sample, use neutral wording, look at ALL the data (not just parts you like), and have someone else review your work.

Key Takeaways

What bias means: a built-in unfairness that skews results
Selection bias: who you chose to ask
Question bias: how you worded the question
Confirmation bias: only seeing data that supports what you already believe

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