lsasim (version 2.1.6)

block_design: Assignment of test items to blocks

Description

block_design creates a length-2 list containing:

• a matrix that identifies which items correspond to which blocks and

• a table of block descriptive statistics.

Usage

block_design(n_blocks = NULL, item_parameters, item_block_matrix = NULL)

Arguments

n_blocks

an integer indicating how many blocks to create.

item_parameters

a data frame of item parameters.

item_block_matrix

a matrix of indicators to assign items to blocks.

Warning

The default item_block_matrix spirals the items across the n_blocks and requires n_blocks >= 3. If n_blocks < 3, item_block_matrix must be specified.

The columns of item_block_matrix represent each block while the rows represent the total number of items. item_block_matrix[1, 1] = 1 indicates that block 1 contains item 1 while item_block_matrix[1, 2] = 0 indicates that block 2 does not contain item 1.

Examples

item_param <- data.frame(item = seq(1:25), b = runif(25, -2, 2))
ib_matrix <- matrix(nrow = 25, ncol = 5, byrow = FALSE,
  c(1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1))
block_design(n_blocks = 5, item_parameters = item_param, item_block_matrix = ib_matrix)
block_design(n_blocks = 5, item_parameters = item_param)