Appl. Math. J. Chinese Univ.

A new family of covariate-adjusted response adaptive designs and their properties ZHANG Li-Xin1 HU Fei-fang2 Abstract. It is often important to incorporate covariate information in the design of clinical trials. In literature there are many designs of using stratification and covariate-adaptive random-ization to balance certain known covariate. Recently, some covariate-adjusted response-adaptive (CARA) designs have been proposed and their asymptotic properties have been studied (Ann. Statist. 2007). However, these CARA designs usually have high variabilities. In this paper, a new family of covariate-adjusted response-adaptive (CARA) designs is presented. It is shown that the new designs have less variables and therefore are more efficient. Response-adaptive designs for clinical trials incorporate sequentially accruing response data into future allocation probabilities. A major objective of response-adaptive designs in clin-ical trials is to minimize the number of patients that is assigned to the inferior treatment to a degree that still generates useful statistical inferences. The preliminary idea of respons