Graphs not only answer research questions, but can spur new ones. Figure 3-9 on page 55 depicts the pattern of changing attitudes, as expressed through Twitter. 

a. On what day and at what time is the highest average positive attitude expressed? 

b. On what day and at what time is the lowest average negative attitude expressed? 

c. What research question(s) do these observations suggest to you with respect to weekdays versus weekends? (Remember, 0 on Sunday is midnight— or late Saturday night.) Name the independent and dependent variables. 

d. How do the researchers operationalize mood? Do you think this is a valid measure of mood? Explain your answer. 

e. One of the highest average negative attitudes occurs at midnight on Sunday. How does this fit with the research hypothesis you developed in part (c)? Does this suggest a new research hypothesis?