An overview of randomization techniques: An unbiased assessment of outcome in clinical research

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• which keeps the numbers of subjects in each group similar at all times.

• groups may be generated that are rarely comparable in terms of certain covariates.

• ddresses the need to control and balance the influence of covariates.

• balance among groups in terms of subjects’ baseline characteristics

• le. Stratified randomization is achieved by generating a separate block for each combination of covari

• This method is used to ensure a balance in sample size across groups over time. Blocks are small and balanced with predetermined group assignments, which keeps the numbers of subjects in each group similar at all times.

• Use of online software to generate randomization code using block randomization procedure will be presented.

• Statistical techniques such as analysis of covariance (ANCOVA), multivariate ANCOVA, or both, are often used to adjust for covariate imbalance in the analysis stage of the clinical research.

• simple randomization, block randomization, stratified randomization, and covariate adaptive randomization

• Blocks are best used in smaller increments as researchers can more easily control balance.

• The stratified randomization method addresses the need to control and balance the influence of covariates.

• This method can be used to achieve balance among groups in terms of subjects’ baseline characteristics (covariates).

• Specific covariates must be identified by the researcher who understands the potential influence each covariate has on the dependent variable.

• Although stratified randomization is a relatively simple and useful technique, especially for smaller clinical trials, it becomes complicated to implement if many covariates must be controlled.

• Stratified randomization has another limitation; it works only when all subjects have been identified before group assignment. However, this method is rarely applicable because clinical research subjects are often enrolled one at a time on a continuous basis. When baseline characteristics of all subjects are not available before assignment, using stratified randomization is difficult.