sim_bmat {flexmet}

Randomly Generate FMP Parameters

Description

Generate monotonic polynomial coefficients for user-specified item complexities and prior distributions.

Usage

sim_bmat(
  n_items,
  k,
  ncat = 2,
  xi_dist = list(runif, min = -1, max = 1),
  omega_dist = list(runif, min = -1, max = 1),
  alpha_dist = list(runif, min = -1, max = 0.5),
  tau_dist = list(runif, min = -3, max = 0)
)

Arguments

n_items

Number of items for which to simulate item parameters.

k

Either a scalar for the item complexity of all items or a vector of length n_items if different items have different item complexities.

ncat

Vector of length n_item giving the number of response categories for each item. If of length 1, all items will have the same number of response categories.

xi_dist

List of information about the distribution from which to randomly sample xi parameters. The first element should be a function that generates random deviates (e.g., runif or rnorm), and further elements should be named arguments to the function.

omega_dist

List of information about the distribution from which to randomly sample omega parameters. The first element should be a function that generates random deviates (e.g., runif or rnorm), and further elements should be named arguments to the function.

alpha_dist

List of information about the distribution from which to randomly sample alpha parameters. The first element should be a function that generates random deviates (e.g., runif or rnorm), and further elements should be named arguments to the function. Ignored if all k = 0.

tau_dist

List of information about the distribution from which to randomly sample tau parameters. The first element should be a function that generates random deviates (e.g., runif or rnorm), and further elements should be named arguments to the function. Ignored if all k = 0.

Details

Randomly generate FMP item parameters for a given k value.

Value

bmat

Item parameters in the b parameterization (polynomial coefficients).

greekmat

Item parameters in the Greek-letter parameterization

Examples

## generate FMP item parameters for 5 dichotomous items all with k = 2
set.seed(2342)
pars <- sim_bmat(n_items = 5, k = 2)
pars$bmat

## generate FMP item parameters for 5 items with varying k values and 
##  varying numbers of response categories
set.seed(2432)
pars <- sim_bmat(n_items = 5, k = c(1, 2, 0, 0, 2), ncat = c(2, 3, 4, 5, 2))
pars$bmat