Chapter 9. Allocation in Randomized Clinical Trials

Olga Kuznetsova^[]

^[] Olga Kuznetsova is Associate Director, Clinical Biostatistics, Merck, USA.

Anastasia Ivanova^[]

^[] Anastasia Ivanova is Associate Professor, Department of Biostatistics, University of North Carolina-Chapel Hill, USA.

This chapter discusses the operationla aspects of randomization designs used in the pharmaceutical industry. Most of this chapter is devoted to the widely used permuted block design and its variations. Allocation procedures that balanced on baseline covariates, such as stratified randomization and covariate-adaptive randomization are also described. All methods are illustrated by examples that include SAS code to generate allocation sequences. Although all of the examples in this chapter refer to clinical trials, the described randomization methods can also be used in a non-clinical setting, i.e., in animal studies.

We refer the reader to Rosenberger and Lachin (2002) for a thorough coverage of other aspects of randomization such as randomization-based inference and covariate-adjusted analysis. A chapter in Senn's book (1997) offers excellent insights on randomization in clinical trials.