Counting Protocols. Adel et al. (1993) applied various orders in drug combination sequence studies in search of a cure for human endometrial carcinoma. Four drugs A–D were evaluated for sequence-dependent inhibition of human tumor colony formation in soft agar.
(a) How many protocols are needed to evaluate all possible sequences of the four drugs?
(b) How many protocols are possible when only two drugs out of four are to be administered if the order of their administration is (i) important or (ii) not important?
(c) A fifth drug, E, is introduced. If drugs A and E cannot be given subsequent to each other because of cumulative toxicity concerns, how many protocols are possible if the order of drug administration is to be evaluated?
Already registered? Login
Not Account? Sign up
Enter your email address to reset your password
Back to Login? Click here