AP Statistics / Unit 1: Exploring One-Variable Data and Collecting Data
1.12 Potential Problems with Sampling
Notes
Bias means a method systematically over- or underestimates.
- Undercoverage: some groups are left out.
- Nonresponse: chosen people don't respond.
- Response bias: answers are inaccurate (wording, lying).
- Voluntary response and convenience samples are biased.
Practice
An online poll anyone can answer suffers from:
People with strong opinions choose to answer.
A phone survey that calls only landlines misses many young people. This is:
Part of the population can't be chosen.
Increasing the sample size fixes bias:
Size reduces variability, not bias.
Ready for more? Take the Unit 1 test.