9.6 Table 9.9 refers to a three-period crossover trial to compare placebo (treatment A) with a low-dose analgesic (treatment B) and high-dose analgesic

(treatment C) for relief of primary dysmenorrhea. Subjects in the study were divided randomly into six groups, the possible sequences for administering the treatments. At the end of each period, each subject rated the treatment as giving no relief (0) or some relief (1). Let yi(k)t = 1 denote relief for subject i using treatment t (t = A,B,C), where subject i is nested in treatment sequence k

(k = 1, . . . , 6).