expectedKL | R Documentation |
Calculates the expected Kullback-Leibler information for an individual question item.
expectedKL(catObj, item)
catObj |
An object of class |
item |
An integer indicating the index of the question item |
The function expectedKL
calculates the expected value of the Kullback-Leibler information
for a specified item where the bounds of integration are \hat{θ} \pm δ,
where δ 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.
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.
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.
Haley Acevedo, Ryden Butler, Josh W. Cutler, Matt Malis, Jacob M. Montgomery, Tom Wilkinson, Erin Rossiter, Min Hee Seo, Alex Weil
likelihoodKL
, posteriorKL
, selectItem
## Loading ltm Cat object data(ltm_cat) ## Store example answers setAnswers(ltm_cat) <- c(1,0,1,0,1, rep(NA, 35)) ## Estimate KL for different unasked items expectedKL(ltm_cat, item = 10) expectedKL(ltm_cat, item = 20) expectedKL(ltm_cat, item = 30)
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