Student Exercise Note: This example involves copying data from a spreadsheet into Statkey. A sample of 50 students were asked about their exercise habits, including hours of exercise per week. The data are stored in a spreadsheet ( ExerciseHours). 1. Download the spreadsheet from the Lock5Stat website. In a browser, go to http://lockSstat.com/datapage.html. Find the ExerciseHours dataset and click on a format (typically xis or csy to download as a spreadsheet). Open the ExerciseHours data in Excel or another spreadsheet/stat package. Copy the data in the Exercise column (including the "Exercise" header). 2. Get into Statkey and copy/paste the data. . If you are already in Statkey click on the Statkey icon to get back. to the main menu. Choose "CI for a Single Mean, Median, St. Dev." Click on "Edit Data" Highlight and delete the default data, paste in the data copied from the spreadsheet. . Check the "Original Sample" to be sure the data pasted properly (n=50, mean =10.6, s=8.043) 3. Find a 95% confidence interval for the mean hours of exercise. Generate a bootstrap distribution with several thousand sample means drawn from the original sample of exercise values. (Note: you can hover over dots in the distribution to see what sample they came from.) Find the standard error (SE) for the means (st. dev. of the bootstrap mean). . Compute a CI using x + 2 * SE. (Note: Be sure to use x from the original sample.) Click on "Two-Tail" to get a version of the CI using percentiles to give the middle 95% of the bootstrap distribution. Is the result reasonably close to what you found above? Click on the blue 0.950 in the middle of the graph and change the confidence level to 0.99 or 0.90. What happens to the width of the interval? BONUS #1: Compare the SE from the bootstrap distribution to s/ vn. BONUS #2: Find a CI for the standard deviation of exercise amounts. Hint: Change the statistic from "Mean" to "Stdev" above the main dotplot