Biased Samples

When the data you see isn’t the whole story

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Survivorship bias: drawing conclusions only from the examples that made it through a filter.
• Selection, non-response and response biases aren’t fixed by larger samples.
• Random sampling, and careful weighting, are the main defences.

Steps

1. The returning planes
2. Holes in the data
3. Old buildings
4. Kinds of bias
5. Reweight the poll
6. A volunteer survey
7. Randomise!