- Verify that the population mean and standard deviation are close to 8 and 1.5 respectively.
- Check the Show Sampling Options box.
- Keep the Number of Samples to 1.
- Set the Sample Size to %n1% to match the class survey.
- Press Draw Samples.
(h) View the ID numbers and sleep time values that were randomly selected from this hypothetical population. The sleep times are graphed in the middle dotplot "Most Recent Sample" (you may need to scroll down). Record the values of the sample mean for this sample from the dotplot. Notice that this sample mean is added to the "Statistic" dotplot.
- Press Draw Samples again.
You will see the second sample mean added to the "Statistic" dotplot. The average of the two sample means is reported as the mean in that dotplot.
- Now change the Number of Samples to 998 (for 1,000 samples total) and press Draw Samples
.
(i) Answer the following questions in your lab report.
- (a) What is the shape of this null distribution?
- (b) Where is it centered? Why does this make sense?
- (c) What is the standard deviation of this null distribution?
3. Strength of evidence
- Change the pull-down menu to Less Than and specify %mean1% (the observed sample mean for your class) in the box, then press Count.
(j) Report the approximate p-value.