This article introduces a dynamical stratified blocked randomized algorithm when the static stratified blocked randomized algorithm is not suitable to resolve the problem caused by uncertain stratified factors and levels during calculation of the sample size at the stage of clinical trial design. Prior to the start of the clinical trial, a list of random numbers is created by blocked randomized algorithm. During field implementation, a block of random numbers is dynamically allocated to a stratify level. Thereafter, a subject is randomized into different groups in that block. The study of Chinese medicine for gastric cancer anemia and blood hypercoagulability is used as an example to illustrate how to design and implement dynamic stratified block randomized algorithm. The results show that the dynamic stratified block randomized algorithm is more flexible and adaptable than the static stratified blocked randomized algorithm. However, its application is more complex and requires higher standards in clinical trials.
