1. Chapter 8: Confidence Intervals for One Population Mean 8.3 Margin of Error

2. Margin of Error for the Estimate of μ The margin of error is equal to half the length of the confidence interval

3. Margin of Error, Precision, & Sample Size The length of a confidence interval for a population mean (and the precision with which xbar estimates μ) is determined by the margin of error. Increasing the sample size increases precision…

4. Sample Size for Estimating μ The sample size required for a (1 – α)-level confidence interval for μ with a specified margin of error: Rounded up to the nearest whole number

5. Example 8.7 Consider the problem of estimating the mean age of all people in the civilian labor force: A. Determine the sample size required to ensure that we can be 95% confident that μ is within 0.5 year of the estimate, xbar. (σ = 12.1 years) B. Find a 95% confidence interval for μ if a sample of the size determined in part (a) has a mean age of 38.8 years.

6. Homework P. 361 33 – 45