Randomize a participant
On the participant page, click Randomize Subject (or Enroll & randomize). In Randomization Review, check the participant and eligibility details, tick the confirmations, enter your password and click Authorize & Randomize. The randomization number is assigned and can never be changed.
Where to find it
Participant page > Randomization > Randomize Subject
Before you start
- You are a Principal Investigator, Sub-Investigator or Study Coordinator with randomization rights.
- The participant is enrolled (or enrolled at randomization), consent is on file and the screening forms are complete.
Randomize
Open the participant and click Randomize Subject on the Randomization card (or Enroll & randomize in the header).
In Randomization Review, check the participant details and the Eligibility crosscheck.
If no eligibility form was entered, tick Final eligibility confirmation.
Tick the consent confirmation and the Investigator authorization.
Enter your password and click Authorize & Randomize.
You see the randomization number. Print confirmation gives a record with the visit schedule and windows.
- The participant becomes Enrolled, and visits timed from randomization are scheduled.
- The chosen roles get an email. It never names the treatment arm.
- Blinded users see "Treatment assignment blinded"; everyone sees the randomization number.
Why randomization is blocked
| Reason shown | What to do |
|---|---|
| "No randomisation list has been loaded" / "no unassigned allocations left" | Ask the unblinded administrator to load or extend the list. |
| "No consent on file" | Have the participant sign eConsent, or record the paper ICF date. |
| "Eligibility form has disqualifying answers" | Correct the answers, or record a screen failure. |
| "Required screening form missing" | Complete the listed screening form. |
| "has no answer for this participant" | Answer the question used for stratification first. |
| "Randomization stopped at this site" | The study team paused randomization at your site. Contact them. |
| "Randomisation cap reached" | The study, country or site cap is full until it is raised. |
| "No randomization cohort is open" | A study manager must open one cohort in Settings > Randomization. |
Questions
Can a randomization be undone?
No. The randomization number is permanently linked to the participant, and the action is signed and recorded in the audit trail.
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Still need help?
Email support@capture.study or use the contact form. Tell us the study name, what you were trying to do and the exact message on screen; a screenshot helps.
Please never send participant names, contact details or health information to support.