In the Multiple Proportions applet:

  • Check the Show Shuffle Options box and press Shuffle Responses. Note that the responses of whether or not to donate are reassigned to the 3 treatment groups and a new Mean Group Diff statistic is calculated (in blue) and added to the dotplot. Select the Plot radio button to see the shuffled segmented bar graph. Press the Shuffle Reponses button four more times and watch how the segmented bar graph changes. Do the shuffled Mean Group Diff statistics tend to be larger or smaller than the one you calculated for the actual research study in part (g)?
  • Now set the number of repetitions to 995 (for 1000 total) and press the Shuffle Responses button.
  • Now, use the applet to determine an estimate for the p-value for this research study by checking the Count Samples box and entering an appropriate direction and value. Include a screen capture of the null distribution with count output displayed in your lab report.

(i) Describe the shape, mean, and standard deviation of this null distribution.

Back Next