Main et al. (A-24) state, “Primary headache is a very common condition and one that nurses encounter in many different care settings. Yet, there is a lack of evidence as to whether advice given to sufferers is effective and what improvements may be expected in the conditions.” The researchers assessed frequency of headaches at the beginning and end of the study for 19 subjects in an intervention group (treatment 1) and 25 subjects in a control group (treatment 2).

Subjects in the intervention group received health education from a nurse, while the control group did not receive education. In the 6 months between pre- and post-evaluation, the subjects kept a headache diary. The following table gives as the response variable the difference (pre –

post) in frequency of headaches over the 6 months for two factors: (1) treatment with two levels

(intervention and control), and (2) migraine status with two levels (migraine sufferer and nonmigraine sufferer).

Change in Frequency of Headaches Migraine Sufferer

(1 = No, 2 = Yes) Treatment Change in Frequency of Headaches Migraine Sufferer

(1 = No, 2 = Yes) Treatment 2 1 1 3 22 2 2 1 6 22 33 1 1 11 1 2 6 2 1 64 1 2 6 2 1 65 1 2 98 1 1 14 1 2 2 2 18 1 2 6 2 16 2 2 Can one conclude on the basis of these data that there is a difference in the reduction of headache frequency between the control and treatment groups? Can one conclude that there is a difference in the reduction of headache frequency between migraine and non-migraine sufferers?
Can one conclude that there is interaction between treatments and migraine status? Let a ¼ :05 for each test.