# simple_ra_probabilities: probabilities of assignment: Simple Random Assignment In DeclareDesign/randomizr: Easy-to-Use Tools for Common Forms of Random Assignment and Sampling

## Description

probabilities of assignment: Simple Random Assignment

## Usage

 ```1 2 3``` ```simple_ra_probabilities(N, prob = NULL, prob_unit = NULL, prob_each = NULL, num_arms = NULL, conditions = NULL, check_inputs = TRUE) ```

## Arguments

 `N` The number of units. N must be a positive integer. (required) `prob` Use for a two-arm design. prob is the probability of assignment to treatment and must be a real number between 0 and 1 inclusive and must be length 1. (optional) `prob_unit` Use for a two-arm design. prob is the probability of assignment to treatment and must be a real number between 0 and 1 inclusive and must be length N. (optional) `prob_each` Use for a multi-arm design in which the values of prob_each determine the probabilities of assignment to each treatment condition. prob_each must be a numeric vector giving the probability of assignment to each condition. All entries must be nonnegative real numbers between 0 and 1 inclusive and the total must sum to 1. It may be a conditions-length vector or a N-by-conditions matrix. (optional) `num_arms` The number of treatment arms. If unspecified, num_arms will be determined from the other arguments. (optional) `conditions` A character vector giving the names of the treatment groups. If unspecified, the treatment groups will be named 0 (for control) and 1 (for treatment) in a two-arm trial and T1, T2, T3, in a multi-arm trial. An exception is a two-group design in which num_arms is set to 2, in which case the condition names are T1 and T2, as in a multi-arm trial with two arms. (optional) `check_inputs` logical. Defaults to TRUE.

## Value

A matrix of probabilities of assignment

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24``` ```# Two Group Designs prob_mat <- simple_ra_probabilities(N=100) head(prob_mat) prob_mat <- simple_ra_probabilities(N=100, prob=0.5) head(prob_mat) prob_mat <- simple_ra_probabilities(N=100, prob_each = c(0.3, 0.7), conditions = c("control", "treatment")) head(prob_mat) # Multi-arm Designs prob_mat <- simple_ra_probabilities(N=100, num_arms=3) head(prob_mat) prob_mat <- simple_ra_probabilities(N=100, prob_each=c(0.3, 0.3, 0.4)) head(prob_mat) prob_mat <- simple_ra_probabilities(N=100, prob_each=c(0.3, 0.3, 0.4), conditions=c("control", "placebo", "treatment")) head(prob_mat) prob_mat <- simple_ra_probabilities(N=100, conditions=c("control", "placebo", "treatment")) head(prob_mat) ```

DeclareDesign/randomizr documentation built on Dec. 7, 2018, 5:10 p.m.