randomizr is designed to make conducting field, lab, survey, or online experiments easier by automating the random assignment process.

Installation from CRAN is easy:

install.packages("randomizr")

If you’d like to install the most current development release, use the following code:

install.packages("devtools")
devtools::install_github("DeclareDesign/randomizr")

There are five main random assignment functions in randomizr: simple_ra(), complete_ra(), block_ra(), cluster_ra(), and block_and_cluster_ra(), which correspond to common experimental designs.

complete_ra() is the workhorse function that will be most appropriate for a large number of experimental situations: it assigns m of N units to treatment:

library(randomizr)
Z <- complete_ra(N = 100, m = 50)
table(Z)
#> Z
#>  0  1 
#> 50 50

A more complicated design that, for example, assigns different numbers of clusters to three different treatments can be accomodated like this:

# This makes a cluster variable: one unit in cluster "a", two in "b"...
clust_var <- rep(letters, times = 1:26)

Z <- cluster_ra(clust_var=clust_var, m_each = c(7, 7, 12),
                condition_names=c("control", "placebo", "treatment"))
table(Z, clust_var)
#>            clust_var
#> Z            a  b  c  d  e  f  g  h  i  j  k  l  m  n  o  p  q  r  s  t  u
#>   control    0  0  0  0  0  0  7  0  0 10 11  0 13 14  0  0  0  0 19  0  0
#>   placebo    0  0  0  4  0  6  0  0  0  0  0  0  0  0  0 16 17 18  0 20  0
#>   treatment  1  2  3  0  5  0  0  8  9  0  0 12  0  0 15  0  0  0  0  0 21
#>            clust_var
#> Z            v  w  x  y  z
#>   control    0 23  0  0  0
#>   placebo   22  0  0  0  0
#>   treatment  0  0 24 25 26

Happy randomizing!