This simple service is suitable for unblinded or single-blind trials with two treatment groups.

Free for 50 randomisations*

Why not try the service out by creating a dummy trial first? This will allow you to become familiar with the way the system works before setting it up for use in your real trial.

* unless you choose a paid option

How it works

Patients are randomised to one of two treatment groups ('A' or 'B') and the result recorded. Randomisation is blocked (using random permuted blocks) to ensure that the groups are balanced periodically.

There is a single password for a trial and anyone with the password may carry out new randomisations for that trial. The randomisation results are shown on-screen and emailed to both the administrator of the trial and to the randomiser. Read the full specification.

Paid options

Trials are initially limited to a maximum of 50 randomisations unless you choose a paid option. With these optional upgrades you can:

  • Increase the randomisation limit above 50
  • Stratify, e.g. by age group or centre
  • Have more than two treatment groups
  • Name your treatment groups, e.g. Placebo and Aspirin rather than A and B
  • Alter the allocation ratio from 1:1, for example to 2:1
  • Add eligibility criteria that must be met to allow randomisation
  • Randomise by text message - try the demo now!

To get your free 50 randomisations make sure you don't choose any of these paid options when creating your trial.

Walkthrough Follow a worked example to create a trial using a randomisation list.

How to cite this service

Sealed Envelope Ltd. 2017. Simple randomisation service. [Online] Available from: [Accessed 23 Feb 2019].

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