Sample proportions and confidence intervals for a population proportion

What this note covers

1. The sample proportion is random
2. Mean and standard deviation of p-hat
3. When the normal approximation works
4. From a point estimate to an interval
5. A complete confidence-interval calculation
6. Interpreting confidence with fixed p
7. Conditions and limits of the approximation
8. Comparing a claimed proportion with an interval

8 sections · 10 key terms & formulas · 6 common mistakes