Clinical trials · Schedule generator

Clinical Trial Randomization List Generator

Create a prospective allocation schedule for two to six treatment groups using independent, fixed-total, or permuted-block randomization.

1. Trial setup

Treatment groups and allocation ratio

Add two to six groups. Ratio components must be whole numbers from 1 to 10.

Code	Treatment label	Ratio	Actions

Reduced ratio: 1:1. Exact totals and every complete block must be divisible by 2.

Randomization method

Maintains the selected ratio within blocks whose sizes vary among the permitted values.

Permitted random block sizes

Suggested for 2 groups at 1:1: 4, 6. Every size must be a multiple of 2.

2. Schedule structure

Use stratified randomizationGenerate a separate schedule within each prespecified stratum.

Total number of allocations

3. Reproducibility and concealment

Master random seed

The same seed and inputs reproduce the same schedule. Treat the seed as concealed information.

4. Results

Enter the trial settings and select Randomize.

Allocation summary by stratum

Schedule preview

Only the first 20 assignments are shown. Use the protected CSV for the complete schedule.

Allocation ID	Stratum	Sequence	Treatment

Suggested methods wording

Protected downloads

The allocation list and audit record contain concealed information. Store and share them securely.

Methods, assumptions, limitations, and references

Important warnings

Planning tool only. This app does not enrol participants or reveal allocations during recruitment. Do not enter participant identifiers or research data.

Allocation concealment: keep the seed, block settings, audit record, and complete schedule away from recruiting personnel.

Independent randomization does not guarantee the requested final treatment totals within a stratum.
Small or disclosed blocks can make future allocations more predictable.
Many treatment groups or sparse strata can produce operationally small allocation cells.

Supported methods

Independent randomization assigns each position independently using probabilities derived from the selected multi-group ratio; final counts can vary. Fixed-total random allocation fixes the requested treatment totals in each stratum and randomly permutes their order. Permuted blocks maintain the complete treatment ratio within every fixed or randomly varying block.

Stratification

Each stratum receives an independently derived reproducible random stream. The same allocation ratio and method apply across strata. Restrict stratification to a small number of important prespecified factors; excessive or sparse strata can create operational difficulties.

Limitations

This tool supports two to six parallel treatment groups. It excludes minimization, response-adaptive and covariate-adaptive procedures, cluster allocation, crossover designs, and live participant randomization. It does not provide access control, sequential disclosure, database audit logging, or regulatory compliance. A generated schedule does not by itself establish adequate allocation concealment.

References

Rosenberger WF, Lachin JM. Randomization in Clinical Trials: Theory and Practice. 2nd ed. Wiley; 2016.
Uschner D, Schindler D, Hilgers RD, Heussen N. randomizeR: An R Package for the Assessment and Implementation of Randomization in Clinical Trials. Journal of Statistical Software. 2018;85(8):1-22.
Schulz KF, Grimes DA. Generation of allocation sequences in randomised trials: chance, not choice. Lancet. 2002;359:515-519.

Suggested citation

Yaacob, N. M., & Ilham, N. A. (2026). Clinical Trial Randomization List Generator (Version 1.1.0) [Web application]. NajibMY. http://127.0.0.1:4321/tools/clinical-trial-randomization/.