assign_treatment: Assign randomized treatment groups

In simulab: Simulates a Wide Variety of Data Shapes, Sizes and Distributions

Assign randomized treatment groups

Description

Randomizes the rows of data to treatment groups, independently within each combination of the strata variables. Balanced assignment allocates the group sizes a stratum is due, rounding the shares to whole units and giving the remainder to the groups with the largest fractional part, then permutes them; unbalanced assignment draws each row independently with probabilities proportional to ratios.

Usage

assign_treatment(
  data,
  groups = 2L,
  balanced = TRUE,
  strata = NULL,
  ratios = NULL,
  name = "treatment",
  seed = NULL
)

Arguments

data	Base data.frame, or a simulab_sim, with at least one row.
groups	Number of treatment groups, as a single whole number of at least 2 (defaulting to 2), or an atomic vector of at least two unique labels. A count of 2 is labeled 0 and 1, and a larger count 1 to groups.
balanced	Use exact allocation within each stratum. A single flag, defaulting to TRUE. FALSE draws each row independently instead, so the realized group sizes vary.
strata	Optional character vector of stratification variables, all present in data. Defaults to NULL, one stratum holding every row.
ratios	Relative allocation ratios, a positive numeric vector with one value per group. Defaults to NULL, equal allocation.
name	Name of the treatment variable, which must not already exist in data. A single non-empty string, defaulting to "treatment".
seed	Optional random seed. A single number, or NULL (the default).

Value

A simulab_sim base data.frame with the columns of data followed by the treatment variable named by name, one row per input row. The component allocation, reached with as.data.frame(x, what = "allocation"), holds one row per stratum and group, with columns stratum, treatment and observations.

Examples

data <- data.frame(id = 1:100, site = rep(c("north", "south"), each = 50))

result <- assign_treatment(data, groups = 2, strata = "site", seed = 1)
head(result)
as.data.frame(result, what = "allocation")

simulab documentation built on Oct. 15, 2026, 5:08 p.m.