Universal Optimality for Selected Crossover Designs
نویسندگان
چکیده
Hedayat and Yang earlier proved that balanced uniform designs in the entire class of crossover designs based on t treatments, n subjects, and pD t periods are universally optimal when n· t .t ¡ 1/=2. Surprisingly, in the class of crossover designs with t treatments and p D t periods, a balanced uniform design may not be universally optimal if the number of subjects exceeds t .t ¡ 1/=2. This article, among other results, shows that (a) a balanced uniform design is universally optimal in the entire class of crossover designs with pD t as long as n is not greater than t .t C 2/=2 and 3 · t · 12; (b) a balanced uniform design with nD 2t , t ̧ 3, and pD t is universally optimal in the entire class of crossover designs with n D 2t and p D t ; and (c) for the case where p · t , the design suggested by Stufken is universally optimal, thus completing Kushner’s result that a Stufken design is universally optimal if n is divisible by t .p¡ 1/.
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