fisherInf {catSurv}

Fisher's Information

Description

Calculates the expected value of the observed information of the likelihood evaluated at the input value \theta.

Usage

fisherInf(catObj, theta, item)

Arguments

catObj

An object of class Cat

theta

A numeric or an integer indicating the potential value for \theta

item

An integer indicating the index of the question item

Details

For the dichotomous case, this Fisher's information is equivalent to the observed information.

Value

The function fisherInf returns a numeric of the expected value of the observed information of the likelihood evaluated at the input value \theta.

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

fisherTestInfo, obsInf, selectItem

Examples

## Loading ltm Cat object
data(ltm_cat)

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

## Fisher's information for different items, at ability parameter of 1
fisherInf(ltm_cat, theta = 1, item = 10)
fisherInf(ltm_cat, theta = 1, item = 20)