🟢 Repeat: Standard Error and Sample Size
Answer without looking:
- SE formula?
- You want to halve your confidence interval width. How much more data?
- What does CLT guarantee about sample means?
Answers: 1. SE = σ / √n 2. 4× the data. Width ∝ 1/√n, so halving requires √n to double, meaning n quadruples. 3. They approach a normal distribution regardless of the underlying data distribution, with mean = population mean and SD = σ/√n.