var,Item-method {irt}

Calculate the variance of an Item

Description

var Returns the variance of an item or multiple items with given parameters for a given ability or abilities, i.e. \theta.

Usage

## S4 method for signature 'Item'
var(x, y = NULL, na.rm = FALSE, use)

## S4 method for signature 'Rasch'
var(x, y = NULL, na.rm = FALSE, use)

## S4 method for signature '1PL'
var(x, y = NULL, na.rm = FALSE, use)

## S4 method for signature '2PL'
var(x, y = NULL, na.rm = FALSE, use)

## S4 method for signature '3PL'
var(x, y = NULL, na.rm = FALSE, use)

## S4 method for signature '4PL'
var(x, y = NULL, na.rm = FALSE, use)

## S4 method for signature 'GRM'
var(x, y = NULL, na.rm = FALSE, use)

## S4 method for signature 'PCM'
var(x, y = NULL, na.rm = FALSE, use)

## S4 method for signature 'GPCM'
var(x, y = NULL, na.rm = FALSE, use)

## S4 method for signature 'GPCM2'
var(x, y = NULL, na.rm = FALSE, use)

Arguments

x

An Item-class or an Itempool-class object containing the item parameters.

y

A numeric vector containing the ability parameters (i.e. theta).

na.rm

Ignored for var(Item, ...)

use

Ignored for var(Item, ...)

Value

Item variances at given theta will be returned.

Author(s)

Emre Gonulates