Question: Since muscle tension in the head region has been associated with tension headaches, you reason that if muscle tension could be reduced, perhaps the headaches would decrease or go away altogether. You design an experiment in which nine participants with tension headaches participate. The participants keep daily logs of the number of headaches they experience during a 2-week base-line period. Then you train them to lower their muscle tension in the head region using a biofeedback device. After 6 weeks of training, during which the participants have been successful at maintaining low muscle tension, they again keep a 2- week log of the number of headaches experienced. The following are the number of headaches recorded during each 2-week period.

Is there evidence, using a two-tailed \(\alpha \) of .05, that the training changed the number of tension headaches? (4 points)