5. To study the effects of two therapeutic regimes (A and B) on 12 hypertensive patients, a researcher randomly assigned patients 1, 2, 5, 8, 9, and 10 to be treated with regime A first, followed by regime B. Patients 3, 4, 6, 7, 11, and 12 were treated with regime B first, followed by treatment A. There is a certain wash-out period between the two regimes. The decrease in systolic blood pressure (SBP, mmHg)

after treatment was recorded. The results are given in Table 10.27.

Please answer the following questions:

(a) What are the treatment factors in this design? What are the factors that are not of interest to the study but should still be considered?

(b) Use appropriate methods to analyze the data.