Balanced allocation function

alloc.balanced first allocates the largest possible number of units to the different groups given their exact target probabilities and then assigns randomly the remaining units to the different groups according to multinomial draws. This method leads to observed allocation probabilities matching the target ones when m*prob is an integer for each group and to observed allocation probabilities (on average) closer to the target ones compared to alloc.simple.

Usage

alloc.balanced(m, prob)

Arguments

m

the 'BATSS' ingredient 'm', a scalar corresponding to the number of participants to be allocated.

prob

the 'BATSS' ingredient 'prob', a named vector of allocation ratios or probabilities.

Value

alloc.balanced returns an object of class factor of length 'm' with levels matching the names of the vector 'prob'.

See also

alloc.simple(), another group allocation function.

Examples

alloc.balanced(100, prob = c(A=.4,B=.6))
#>   [1] A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A
#>  [38] A A A B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B
#>  [75] B B B B B B B B B B B B B B B B B B B B B B B B B B
#> Levels: A B
table(alloc.balanced(100, prob = c(A=.4,B=.6)))
#> 
#>  A  B 
#> 40 60 
table(alloc.balanced(100, prob = c(A=.4,B=.6)))
#> 
#>  A  B 
#> 40 60