Randomisation list generator
Create a reproducible allocation list for a trial with simple or permuted-block randomisation, two to six arms and a seed you can publish.
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This calculator needs JavaScript, because it calculates in your browser and sends nothing. Turn JavaScript on to use it. How it is calculated is explained below.
- Seed (use it to repeat this list)
- Participants per arm
- Allocation list (number, arm)
How it is calculated
A seeded generator makes the list reproducible. Permuted blocks keep the arms balanced after every block; the last block may be cut short, so the final counts can differ slightly.
Arms are called A, B, C and so on. Allocation concealment and who holds the list matter as much as the sequence.
Block: every block holds each arm equally often, in random order (Fisher–Yates shuffle)Simple: each participant is assigned to a random arm
Worked example: 8 participants, 2 arms, blocks of 4, seed 99: four to arm A and four to arm B, in the same order every time.
Sources
- Suresh K. An overview of randomization techniques: an unbiased assessment of outcome in clinical research. J Hum Reprod Sci. 2011.
- Durstenfeld R. Algorithm 235: Random permutation. Commun ACM. 1964.
These calculators support research; they do not replace the advice of a statistician or a clinician.
Questions
Can I use this list in a real trial?
It gives a correct, reproducible sequence. In a real trial the sequence should be generated and kept by someone who does not enrol participants, so that allocation stays concealed.