Important use note
BioRand is a local browser-based planning tool. In seeded mode, anyone who knows the seed and settings can reproduce the sequence. Masking in this tool is not a substitute for a secure, centralized allocation-concealment system in a regulated clinical trial. For a real study, pre-specify the method, keep the master key with an independent authorized person, and preserve the complete audit trail.
Select the randomization method
Choose the method before entering the study parameters. The help text explains when each method is appropriate.
How should I choose?
Fixed blocks are useful when periodic balance is important and allocation concealment is adequately protected.
Variable blocks are generally preferable when staff might predict the next allocation.
Use stratification only for a small number of clearly prognostic factors; too many strata create very small cells.
Simple randomization is often adequate for large samples, while the MTI-constrained method is useful when you want randomization with a limit on imbalance.
Define study parameters
Complete the fields below. Every field has an explanation and an example. The plan cannot be generated until all required information is valid.
Separate names with commas. Use unique names, for example: Control, Low dose, High dose.
What does this mean?
Use positive whole numbers in the same order as the groups. Example: 1:2:1.
What does this mean?
Enter the total number of experimental units to be assigned.
What does this mean?
The block size must be a multiple of the sum of the normalized allocation ratios.
What does this mean?
Select at least two sizes. A size is randomly selected for each complete block.
What does this mean?
The probability shift begins when the spread of observed-versus-expected deviations reaches this value.
What does this mean?
Use existing IDs when the order of actual enrolled units is already known.
What does this mean?
Example: RAT-, PATIENT- or FARM-A-. It is added before the sequential number.
What does this mean?
For non-stratified methods, enter one subject ID per line. For stratified randomization, enter Subject_ID and the exact stratum label separated by a comma or tab.
What does this mean?
Enter one factor per line. The program creates every combination of the levels.
What does this mean?
For a planned sequence, enter a quota for every stratum. For known subjects, use the existing-record option above.
How should these numbers be interpreted?
Same settings and seed reproduce the same exported sequence. This mode is not unpredictable to someone who knows the seed.
What does this mean?
In seeded mode, this value is the reproducibility key. In crypto mode it is only a run identifier.
What does this mean?
What does this mean?
Randomization report
The participant-facing table and CSV contain masked groups when masking is enabled. Use the separate master-key action only for authorized unblinding.
Allocation distribution
Bars show the observed number and percentage. Compare the observed count with the expected count rather than judging balance from the picture alone.
| Group | Expected N | Observed N | Observed % | Deviation |
|---|
Stratum summary
| Stratum | N | Group counts |
|---|
Master key (authorized use only)
Do not print or distribute this section with masked labels. The separate key download contains the same mapping.
| Masked label | Real group |
|---|
| Subject ID | Stratum | Block / step | Assigned group | Label code |
|---|