tcc: computes a test characteristic curve (tcc)

In lordif: Logistic Ordinal Regression Differential Item Functioning using IRT

Description

computes a test characteristic curve (tcc) from input item parameters

Usage

  tcc(a, cb, theta, model = "GRM")

Arguments

a	a vector of slope parameters
cb	a matrix of category boundary/threshold parameters
theta	a grid of theta values
model	IRT model, either "GRM" or "GPCM"

Details

Either the graded response model (GRM) or the generalized partial credit model (GPCM) can be specified. The lowest response/score for each item is coded as 0 not 1.

Value

Retruns a vector of tcc values over a theta grid

Author(s)

Seung W. Choi <[e-mail]>

See Also

probgrm, probgpcm

Examples

## Not run: tcc(a,cb,theta,model="GRM")
## Not run: tcc(a,cb,theta,model="GPCM")

Example output

Loading required package: mirt
Loading required package: stats4
Loading required package: lattice
Loading required package: rms
Loading required package: Hmisc
Loading required package: survival
Loading required package: Formula
Loading required package: ggplot2

Attaching package: 'Hmisc'

The following objects are masked from 'package:base':

    format.pval, units

Loading required package: SparseM

Attaching package: 'SparseM'

The following object is masked from 'package:base':

    backsolve

lordif documentation built on May 2, 2019, 2:13 p.m.