Welcome to Randomization.com!!!
(where it's never the same thing twice)

There are now three randomization plan generators.

The first (and original) generator randomizes each subject to a single treatment by using the method of randomly permuted blocks. Now with random block sizes!!!

March 29, 2013: A small problem with the code that has been corrected*. Its effect, if any, would be to interfere with reproducing a randomization plan when random block sizes were used, there were more block sizes (sizes, not blocks) than treatments, and many plans were generated at once. Otherwise, results should be unchanged. When there is only one block size, both version with random block sizes should produce the same results as the original generator, which allowed for only one block size. Click on the appropriate link to access the generator that was featured through August 2, 2007 or through March 29, 2013.

The second generator creates random permutations of treatments for situations where subjects are to receive all of the treatments in random order.

The third generator generates a random permutation of integers. This is particularly useful for selecting a sample without replacement.


New features will be added as the occasion demands. This page will undergo updates and revisions, but links to the randomization plan generators will always be available here, The generators may undergo some cosmetic changes, but the algorithms will not be changed. This will insure that an old plan can always be reconstructed. In the event it becomes necessary to change a generator, a notice will be posted on the website and the program will be updated, but every version of the generators will continue to be available. When a randomization plan is created, the date is now printed on the plan to document the generator that was used.

Newly added! Random block sizes

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August 3, 2007