solution

13.  
Estimation:

 a. Use the 2SD method to
approximate a 95% confidence interval for the difference in long-run mean
improvement score for subjects who get unrestricted sleep minus the long-run
mean improvement score for subjects who are sleep deprived. (Hints: Remember
the observed value of the difference in group means and obtain the SD of the
difference in group means from the applet’s simulation results. The interval
should be observed difference in means ±2SD, where SD represents the standard
deviation of the null distribution of the difference in group means.)

b. Interpret what this confidence
interval reveals, paying particular attention to whether the interval is
entirely positive, entirely negative, or contains zero. (Hint: Be sure to
convey “direction” in your interpretation by saying how much larger improvement
scores are on average for the treatment you find to have the larger long-run
mean: I’m 95% confident that the long-run mean improvement score is __________
to ________ higher with the _________ treatment as opposed to the _________
treatment.)