Goals of this exercise: This exercise will help you determine how accurate a sample mean is likely to be, and how this accuracy is related to the sample size.

 What do I need to know? To make best use of this exercise, you should know how to use a z table to find probabilities on a normal distribution, and how to calculate the standard error of a mean. Relevant review materials are available from the links below.

 What do I need? You will need a table for the standardized normal distribution (z) and the WISE Sampling Distribution applet. The Sampling Distribution applet is a small program, which loads into your computer. Because it is on your local computer, it responds very quickly to your input. It will offer you many choices, and you will see the results of your choices immediately. Feel free to experiment with the applet.

Answers to questions: You will be asked to answer several questions. Approximate answers are provided so you can check your work. Detailed solutions are available, but you should try to answer the questions on your own before consulting the detailed solutions. You will learn much more by doing the exercises yourself than if you merely read them and the answers. 

• Go to the Sampling Distributions applet
• An overview of the applet
• Begin the Exercise: Accuracy of sample means
• Introduction to the Applet
• Review of z-scores
• Review of Central Limit Theorem
• Answers for Exercise 1 hand calculation problems
• Follow up questions: Questions to assess knowledge
• Download the exercise.

Questions, comments, difficulties? Please contact Dale Berger.