grmtree (version 0.1.0)

grmfit: Internal Function: Fit Graded Response Model

Description

Fits a graded response model (GRM) to item response data. This is an internal function called by grmtree and is not intended to be used directly.

Usage

grmfit(
  y,
  x = NULL,
  start = NULL,
  weights = NULL,
  offset = NULL,
  ...,
  estfun = FALSE,
  object = FALSE
)

Value

A list containing:

coefficients

Item parameter estimates

objfun

Negative log-likelihood value

estfun

Empirical estimating functions if requested

object

Full mirt model object if requested

Arguments

y

A matrix of item responses (rows = persons, columns = items)

x

Optional predictor matrix (not currently used)

start

Optional starting values (passed to mirt)

weights

Optional case weights (not currently used)

offset

Optional offset (not currently used)

...

Additional arguments passed to mirt::mirt

estfun

Logical indicating whether to compute empirical estimating functions

object

Logical indicating whether to return the full mirt model object