Do It Yourself!: Interpreting Confidence Intervals

Click on the "One Sample" button to generate a random sample from a population with mean of mu = 750 and standard deviation sigma = 35. The applet calculates and displays the 95% confidence interval for the population mean. Click on the "10 Samples" button to see 10 confidence intervals for 10 different samples. Then click on the "100 Samples" to see a visual display of 100 confidence intervals. The ones in red do not include the true mean. For a 95% confidence interval, only about 5% should not include the true mean. The white vertical grid lines are spaced one standard error apart.

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The applet(s) on this page is from Seeing Statistics,™ an online, interactive statistics textbook. Seeing Statistics is a registered service mark used herein under license. The applet(s) on this page was designed to be used exclusively with Introduction to Probability and Statistics, Eleventh Edition, by Mendenhall, Beaver, & Beaver. (c) 2003, Duxbury Thomson Learning. The applet(s) on this page may not be copied, duplicated, or reproduced for any reason.