An example of block randomization involves assigning nine participants to three conditions: A, B, and C. A pre-generated sequence might have a first block of A, C, B, a second block of B, C, A, and a third block of C, B, A. The first participant is assigned to condition A, the second to condition C, the third to condition B, and so forth, guaranteeing that after every three participants, the conditions have perfectly equal sample sizes.