FSM (version 1.0.0)

som: Selection Order Matrix (SOM)

Description

Generates a Selection Order Matrix (SOM) in a deterministic/random manner.

Usage

som(
  data_frame = NULL,
  n_treat,
  treat_sizes,
  include_discard = FALSE,
  method = "SCOMARS",
  control = FALSE,
  marginal_treat = NULL
)

Arguments

data_frame

A (optional) data frame corresponding to the full sample of units. Required if include_discard = TRUE.

n_treat

Number of treatment groups.

treat_sizes

A vector of treatment group sizes. If control = TRUE, the first element of treat_sizes should be the control group size.

include_discard

TRUE if a discard group is considered.

method

Specifies the selection strategy used among 'global percentage', 'randomized chunk', 'SCOMARS'. 'SCOMARS' is applicable only if n_treat = 2.

control

If TRUE, treatments are labeled as 0,1,...,g-1 (0 representing the control group). If FALSE, they are labeled as 1,2,...,g.

marginal_treat

A vector of marginal probabilities, the jth element being the probability that treatment group (or treatment group 2 in case control = FALSE) gets to choose at the jth stage given the total number of choices made by treatment group upto the (j-1)th stage. Only applicable when method = 'SCOMARS'.

Value

A data frame containing the selection order of treatments, i.e. the labels of treatment groups at each stage of selection. If method = 'SCOMARS', the data frame contains an additional column of the conditional selection probabilities.

References

Chattopadhyay, A., Morris, C. N., and Zubizarreta, J. R. (2020), ``Randomized and Balanced Allocation of Units into Treatment Groups Using the Finite Selection Model for R''.

Morris, C. (1983), ``Sequentially controlled Markovian random sampling (SCOMARS)'', Institute of Mathematical Statistics Bulletin,12(5), 237.

Examples

# NOT RUN {
# Generate an SOM with N = 12, n1 = n2 = 6.
som_sample = som(data_frame = NULL, n_treat = 2, treat_sizes = c(6,6), include_discard = FALSE, 
method = 'SCOMARS', control = FALSE, marginal_treat = rep(6/12,12))
# }