ThurMod (version 1.1.11)

mod.matrices: Create model matrices for Thurstonian modeling

Description

This function creates and returns model matrices of Thurstonian model equations.

Usage

mod.matrices(blocks, itf, model)

Value

Returns a list of elements containing model matrix information.

Arguments

blocks

A matrix defining the blocks of the model. The number of rows must be the number of blocks, each row represents a block and contains the item numbers. The number of columns present the number of items per block.

itf

A vector defining the items-to-factor relation. For example `c(1,1,1,2,2,2)` defines six items, the first three correspond to factor 1, the second three correspond to factor 2.

model

A descriptor for the model. Can be one of `'lmean'`, `'uc'`, `'irt'` or `'simple2'`, `'simple3'` or `'simple5'`. The Number behind the `'simple'` statement defines the Thurstone case.

Examples

# set seed and define blocks
set.seed(1)
blocks <- matrix(sample(1:15,15), ncol = 3)

# define the item-to-factor relation
itf <- rep(1:3,5)

mod.matrices(blocks,itf,'irt')