Block urn design - a new randomization algorithm for sequential trials with two or more treatments and balanced or...

Area of Science:

• Clinical Trials Methodology
• Biostatistics
• Randomization Techniques

Background:

• Permuted block design is widely used in clinical trials for its simplicity and imbalance control, but carries a risk of selection bias due to deterministic assignments.
• Existing alternatives like biased coin and urn designs offer better randomness but lack consistent imbalance control.
• Other advanced designs, such as big stick and maximal procedures, have limitations in applicability or complexity.

Purpose of the Study:

• To introduce a novel randomization method, the block urn design, that integrates the strengths of existing approaches.
• To address the limitations of current randomization techniques in controlling treatment imbalances and ensuring allocation randomness.
• To provide an easily implementable design for sequential clinical trials with multiple treatments and unbalanced allocations.

Main Methods:

• Development of the block urn design algorithm.
• Analytical assessment of the statistical properties of the block urn design.
• Computer simulations comparing the block urn design against established randomization methods.

Main Results:

• The block urn design demonstrates consistent control over treatment imbalances.
• The new design achieves high allocation randomness, mitigating selection bias concerns.
• Simulations confirm the superior performance of the block urn design compared to existing methods.

Conclusions:

• The block urn design effectively combines consistent imbalance control and high allocation randomness.
• This novel method is suitable for a wide range of clinical trial scenarios, including those with multiple treatments and unbalanced allocations.
• The block urn design offers a practical and robust solution for improving randomization in clinical trials.