Lesson 2: Confidence Intervals and Sample Size

Overview Section

Using the result of confidence intervals from the last lesson, this lesson starts with a discussion on selecting sample size for estimating the population mean as well as the population total by a confidence interval with a specified margin of error and specified level of confidence. In the second section, the confidence interval for estimating a population proportion is discussed. In the last section, sample sizes needed for estimating a population proportion are discussed. Both the educated guess and conservative method are introduced.

Lesson 2:  Ch. 4.1-4.2, 5.1-5.3, of Sampling by Steven Thompson, 3rd edition.

Objectives

Upon completion of this lesson, you should be able to:

  • find the sample size needed for estimating population mean and population total
  • know how to compute the confidence interval for population proportion
  • find the sample size needed for estimating population proportion by both the educated guess method and conservative method
  • find the sample size to estimate population proportion, and
  • know when to use educated guess method and when to use conservative method