Permuted-block randomization with varying block sizes using SAS® Proc Plan

Permuted-block randomization with varying block sizes using SAS® Proc Plan Permuted-block randomization is often used in determining treatment assignments for clinical trials. This method allows flexibility in achieving balanced allocation of subjects among treatment groups and is further enhanced with increased randomness of the assignments by the use of varying block sizes. Chow and Liu (2004) illustrated the implementation of the permutedblock randomization with a fixed block size using the SAS PROC PLAN. This paper presents a modified version of their SAS program to implement the permuted-block randomization with varying block sizes. This program is simple to run and self-contained. Users can easily adapt the program to meet various design specifications, produce analytical statistics and present the generated randomization schedule in a desired format.