What you'll learn
How to use a sample to make and test statements about a population.
Estimation
- A sample is used to estimate a population value (e.g. the sample mean estimates the population mean).
- Larger, well-chosen samples give more reliable estimates and reduce bias.
Hypothesis testing (informal)
- State a clear hypothesis (a claim to test).
- Collect suitable data and compare the results with what the hypothesis predicts.
- Decide whether the evidence supports or does not support the hypothesis, and evaluate the reliability of the conclusion.
Exam tips
- Always relate the conclusion back to the original hypothesis.
- Comment on sample size and possible bias when judging reliability.
Common mistakes
- Stating a conclusion without evidence from the data.
- Ignoring the effect of a small or biased sample.