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Clinical Trial Randomization Tool

  • This tool can create randomized arm allocation sequences for a trial using maximal randomization.
  • To create a new randomized trial, enter the randomization parameters for your trial, then click "Request Confirmation Email."
  • You will receive a confirmation email with instructions on how to download your trial's results.
  • For more detailed instructions, you may view the Tool Instructions page.

Trial Overview
A short identifier for your trial. When your randomized assignments are downloaded, the files will be labeled with this name.
Trial Arms
The number of arms in this trial.

Arm count can be between 2 and 4, inclusive.

The ratio of participants assigned to each arm, relative to other arms. Allocation Ratio:
Name of Arm:
For each arm, enter the ratio of participants assigned to it, relative to other arms. Also assign a name to each arm. Arm Allocation Ratios and Names

Arm 1:

Arm 2:


At any point in the randomization process, for any stratification group, no trial arm will be assigned more than this many participants than any other arm.

MTI can be any number between (twice the largest allocation ratio) and 20.

Stratification and Trial Size
Stratify Trial?
If you are planning to stratify your trial, click Yes below then enter the strata information in the inputs that appear.
The total number of participants in your trial.

Max: 100,000

How many stratification variables are you using?

Max: 5

For each variable, indicate how many possible values/categories it will have. Maximum 15 per variable. How Many Categories?
Name of Variable:
For each variable, indicate how many possible values/categories it will have. Maximum 15 per variable. Also name each variable. Variable Categories and Names

Variable 1:


The number of stratification groups. This is the product of the number of categories for all variables above.

Max: 200


The number of participants of the largest stratification group of your trial. This many assignments will be generated for each of your specified groups.

The total number of participants in your trial.

Max: 100,000

Stratification Variable Category Names
Gender (2)
Strata Category Permutations

Your resulting strata will have the following names. Short names are enforced due to limitations in Microsoft Excel.

Contact Info

We will email you at this address when your results are ready!

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