irt (version 0.2.9)

var,Item-method: 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 Item
var(x, y = NULL, na.rm = FALSE, use)
# S4 method for Rasch
var(x, y = NULL, na.rm = FALSE, use)
# S4 method for 1PL
var(x, y = NULL, na.rm = FALSE, use)
# S4 method for 2PL
var(x, y = NULL, na.rm = FALSE, use)
# S4 method for 3PL
var(x, y = NULL, na.rm = FALSE, use)
# S4 method for 4PL
var(x, y = NULL, na.rm = FALSE, use)
# S4 method for GRM
var(x, y = NULL, na.rm = FALSE, use)
# S4 method for PCM
var(x, y = NULL, na.rm = FALSE, use)
# S4 method for GPCM
var(x, y = NULL, na.rm = FALSE, use)
# S4 method for GPCM2
var(x, y = NULL, na.rm = FALSE, use)

Value

Item variances at given theta will be returned.

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, ...)

Author

Emre Gonulates