IRTest (version 2.1.0)

plot_item: Plot of item response functions

Description

This function draws item response functions of an item of the fitted model.

Usage

plot_item(x, item.number = 1, type = NULL)

Value

This function returns a plot of item response functions.

Arguments

x

A model fit object from either IRTest_Dich, IRTest_Poly, IRTest_Cont, or IRTest_Mix.

item.number

A numeric value indicating the item number.

type

A character string required if inherits(x, c("mix")) == TRUE. It should be either "d" (dichotomous item) or "p" (polytomous item); item.number=1, type="d" indicates the first dichotomous item.

Author

Seewoo Li

Examples

# \donttest{
# A preparation of dichotomous item response data

data <- DataGeneration(N=500, nitem_D = 10)$data_D

# Analysis

M1 <- IRTest_Dich(data)

# Plotting item response function

plot_item(M1, item.number = 1)
# }