In the statistical theory of the design of experiments, blocking is the arranging of experimental units in groups (blocks) that are similar to one another. Typically, a blocking factor is a source of variability that is not of primary interest to the experimenter. An example of a blocking factor might be the sex of a patient; by blocking on sex, this source of variability is controlled for, thus leading to greater accuracy.
the subject number for each block.
number of strata.
the size ratio for each arm.
fixed schedule: use a fixed seed in R to generate the same simulation results.
random schedule: use a random seed in R to generate the different simulation results.
R Core Team (2013). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria.