Principal investigator: Aiyi Liu, Ph.D.
Sequential and adaptive methods are commonly used in medical clinical trials. The former ensure early stopping of a trial if efficacy of a treatment is evident, and the latter, being sequential in nature, are used to modify the design of the trial based on current observed data to ensure that initial design requirements are met. Research directions in this area are broad, including developing sequential testing methods useful in a specific medical area, efficient post-trial inference procedures for data analysis such as point estimation, confidence intervals, p-values, incorporation of overrunning data, and analysis of secondary endpoints. Adaptive methods are being developed for bivariate phase II trials for both response and toxicity, and for phase III studies with longitudinal outcomes. Research focuses on both phase II and III studies, univariate and multivariate endpoints, and group and fully sequential designs.
 
DESPR Collaborators

· James F. Troendle, Ph.D.
· Kai F. Yu, Ph.D.
· Mi-Xia Wu, Ph.D.

Selected Publications

Troendle JF, Liu A, Wu CQ, & Yu KF. (2005). Sequential testing for efficacy in clinical trials with non-transient effects. Statistics in Medicine, 24(21):3239-3250. [Abstract]

Liu A, Troendle JF, Yu KF, & Yuan V. (2004). Conditional maximum likelihood estimation following a group sequential test. Biometrical Journal, 46:760-768.

Wu CQ, Liu A, & Yu KF. (2005). Estimation of secondary parameters after a multivariate group sequential test. In Fan J and Li G (Eds.), Contemporary Multivariate Analysis and Experimental Design in Honor of Professor Kai-Tai Fang's 65th Birthday (pp.337-350). The World Scientific Publisher.

Liu A, Wu C, Yu K, & Gehan E. (2005). Supplementary analysis of probabilities at the termination of a group sequential phase II trial. Statistics in Medicine, 24:1009-1027. [Abstract]

Liu A. (2003). A simple low-bias estimate following a sequential test with linear boundaries. In Kolassa J and Oakes D (Eds.), Crossing Boundaries: Statistical Essays in Honor of Jack Hall (pp.47-58). IMS Monograph Series.

Mazumdar M & Liu A. (2003). Group sequential design for comparative diagnostic accuracy studies. Statistics in Medicine, 22:727-739. [Abstract]

Hall WJ & Liu A. (2002). Sequential tests and estimates after overrunning based on maximum-likelihood ordering. Biometrika, 89:699-707.