Identifying Causes: headaches. You are trying to identify the cause of late-afternoon headaches that plague you several days each week.

For each of the following tests and observations, explain which of the six guidelines for establishing causality you used and what you concluded. Then summarize your overall conclusion based on all the observations.

a. The headaches occur only on days that you go to work.

b. If you stop drinking Coke at lunch, the headaches persist.

c. In the summer, the headaches occur less frequently if you open the windows of your office slightly. They occur even less often if you open the windows of your office fully.