expectedKL {catSurv} R Documentation

## Expected Kullback-Leibler Information

### Description

Calculates the expected Kullback-Leibler information for an individual question item.

### Usage

expectedKL(catObj, item)


### Arguments

 catObj An object of class Cat item An integer indicating the index of the question item

### Details

The function expectedKL calculates the expected value of the Kullback-Leibler information for a specified item where the bounds of integration are \hat{\theta} \pm \delta, where \delta is qnorm(z) times the square root of the Fisher test information and z is specified in the z slot of the Cat object. See Note for more information on integration.

### Value

The function expectedKL returns a numeric indicating the expected Kullback-Leibler information for the specified item, given the current answer profile and ability parameter estimate.

### Note

This function is to allow users to access the internal functions of the package. During item selection, all calculations are done in compiled C++ code.

This function uses adaptive quadrature methods from the GNU Scientific Library (GSL) to approximate single-dimensional integrals with high accuracy.

### Author(s)

Haley Acevedo, Ryden Butler, Josh W. Cutler, Matt Malis, Jacob M. Montgomery, Tom Wilkinson, Erin Rossiter, Min Hee Seo, Alex Weil

likelihoodKL, posteriorKL, selectItem

### Examples

## Loading ltm Cat object
data(ltm_cat)