psychotools (version 0.7-4)

rpcm: Simulate Data under a Partial Credit Model

Description

rpcm simulates IRT data under a partial credit model.

Usage

rpcm(theta, delta, nullcats = FALSE, return_setting = TRUE)

Value

rpcm returns either a list of the following components:

delta

list of numeric vectors of item threshold parameters used,

theta

numeric vector of person parameters used,

data

numeric matrix containing the simulated data,

or (if return_setting = FALSE) only the numeric matrix containing the simulated data.

Arguments

theta

numeric vector of person parameters. Can also be a list, then a list of length length(theta) is returned, containing multiple simulated data sets.

delta

list of numeric vectors of item threshold parameters.

nullcats

logical. Should null categories be allowed?

return_setting

logical. Should a list containing slots of "delta", and "theta", as well as the simulated data matrix "data" be returned (default) or only the simulated data matrix?

See Also

rgpcm, rrsm, rrm, rpl

Examples

set.seed(1)
## item responses under a partial credit model (PCM) with
## 6 persons with three different person parameters
## 8 items with different combinations of two or three threshold parameters
ppar <- rep(-1:1, each = 2)
tpar <- rep(list(-2:0, -1:1, 0:1, 0:2), each = 2)
sim <- rpcm(theta = ppar, delta = tpar)

## simulated item response data along with setting parameters
sim

## print and plot corresponding item response object
iresp <- itemresp(sim$data)
iresp
plot(iresp)