expectedPV {catSurv}

Expected Posterior Variance

Description

Estimates the expected posterior variance for a respondent's estimated ability parameter for an item yet to be answered based on a respondent's ability parameter estimate from the already-answered items.

Usage

expectedPV(catObj, item)

Arguments

catObj

An object of class Cat

item

An integer indicating the index of the question item

Value

The function expectedPV returns a numeric value indicating a respondent's expected posterior variance for an unasked item.

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.

Author(s)

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

See Also

estimateSE, probability, selectItem

Examples

## Loading ltm Cat object
data(ltm_cat)

## Store example answers
setAnswers(ltm_cat) <- c(1,0,1,0,1, rep(NA, 35))

## Estimate EPV for different unasked items
expectedPV(ltm_cat, item = 10)
expectedPV(ltm_cat, item = 20)
expectedPV(ltm_cat, item = 30)