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 methods are introduced.

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


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

  1. Calculate the sample size needed for estimating population mean and population total,
  2. compute the confidence interval for population proportion,
  3. Given a desired level of confidence for estimating a population proportion, determine the sample size required using both the educated guess method and conservative method, and critically evaluate the advantages and disadvantages of both approaches,
  4. Determine the necessary sample size to estimate the population proportion, and
  5. Choose between using the educated guess method and the conservative method.