Reconsider Exercise 9.1.15 on video type and emotion. Besides assessing their subjects’ emotional state after watching the videos, they also assessed their mood. The results can be found in the data set VideoMood with the higher the mood score, the better the subject’s mood.

a. Identify the explanatory variable and the response variable in this study.
b. State, in words or symbols, the null and alternative hypotheses.
c. Put the data in the Multiple Means applet and describe what the dotplots tell us about the association between type of video and a person’s mood.
d. Find the MAD statistic. What is that number describing?
e. Use a simulation-based approach to test whether video type affects a person’s mood. Be sure to report a p-value.
f. Based on the p-value, state an appropriate conclusion in the context of the study. Be sure to comment on statistical significance, causation, and generalization along with how you are making your decision.

Data from previous exercise

Student researchers at Hope College studied the effects of watching certain types of videos on a person’s emotional state. The subjects were randomly shown a short happy video (babies laughing), a short sad video (abused dogs in a shelter), or no video. Aft er this, the subjects were given an assessment of their emotional state with high numbers representing “good emotional state.” The results can be found in the data set VideoEmotion.