gpcm: Generalised Partial Credit Model Derived Probabilities
In classify: Classification Accuracy and Consistency under IRT models.

Description Usage Arguments Details Value Examples

Calculate vector of probabilities of success from person and item parameters under the Generalised Partial Credit Model.

1	gpcm(theta=NULL,alpha=NULL,delta=NULL,n=NULL)

`theta`	Theta parameter
`alpha`	Alpha parameter
`delta`	Vector of delta parameters
`n`	Number of item categories

The delta parameters are the intersection points of adjacent category information functions. There should be one less delta parameter than categories. Assumes that the location parameter is zero

Vector of probabilities of success

## Generalized Partial Credit Model
## Item parameters from Embretson & Reise (2000, p. 112) item 5
theta <- 1
alpha <- .683
delta <- c(-3.513,-.041,.182)
n <- 4
gpcm(theta,alpha,delta,n)