How to use this calculator
Choose simple, balanced, block, or factorial design; enter unit IDs or block labels and a seed.
Formula and method
Simple: independent Bernoulli(0.5) per unit. Balanced: shuffle a near-equal label list. Block: repeat balanced allocation inside each block. Factorial: randomize 2×2 cell run order.
Worked example
Six units in balanced mode assign three to each group, reproducibly for a fixed seed.
Assumptions and supported scope
2–500 unique unit IDs; factorial 1–100 replicates per cell. Odd balanced groups give the extra assignment to treatment B. Pseudorandom, not suitable for security or concealed clinical allocation.
Method references
Method and worked example checked against the calculator implementation. About our methods · Report a correction