Package index

Getting Started

New to irtQ? Start here with core data structures.

irtQ-package irtQ

irtQ: Unidimensional Item Response Theory Modeling

shape_df()

Create a Data Frame of Item Metadata

shape_df_fipc()

Combine fixed and new item metadata for fixed-item parameter calibration (FIPC)

Item Parameter Estimation

Calibrate item parameters using marginal maximum likelihood (MMLE-EM) and fixed ability methods.

est_irt()

Item parameter estimation using MMLE-EM algorithm

est_mg()

Multiple-group item calibration using MMLE-EM algorithm

est_item()

Fixed ability parameter calibration

getirt()

Extract Components from 'est_irt', 'est_mg', or 'est_item' Objects

Ability Estimation & Scoring

Estimate examinee ability scores from item response data.

est_score()

Estimate examinees' ability (proficiency) parameters

llike_score()

Log-Likelihood of Ability Parameters

Model-Data Fit Evaluation

Assess how well the fitted IRT model describes the observed data.

irtfit()

Traditional IRT Item Fit Statistics

sx2_fit()

S-X2 Fit Statistic

plot(<irtfit>)

Draw Raw and Standardized Residual Plots

Differential Item Functioning (DIF)

Detect item bias across examinee groups using residual-based and CATSIB methods.

rdif()

IRT Residual-Based Differential Item Functioning (RDIF) Detection Framework

crdif()

Residual-Based DIF Detection Framework Using Categorical Residuals (RDIF-CR)

grdif()

Generalized IRT residual-based DIF detection framework for multiple groups (GRDIF)

catsib()

CATSIB DIF Detection Procedure

Item Parameter Drift (IPD)

Detect and evaluate item parameter drift across test administrations.

ripd()

Residual-based Item Parameter Drift (RIPD) Detection Framework

pcd2()

Pseudo-count D2 method

Classification Accuracy & Consistency

Evaluate the reliability of cut-score-based pass/fail classifications.

cac_lee()

Classification Accuracy and Consistency Using Lee's (2010) Approach

cac_rud()

Classification Accuracy and Consistency Based on Rudner's (2001, 2005) Approach

Information & Characteristic Functions

Compute and visualize item/test information functions and characteristic curves.

info()

Item and Test Information Function

traceline()

Compute Item/Test Characteristic Functions

plot(<info>)

Plot Item and Test Information Functions

plot(<traceline>)

Plot Item and Test Characteristic Curves

Multistage-Adaptive Test (MST)

Simulate MST administrations, evaluate panel performance, and compute TIF-based routing cut scores.

reval_mst()

Recursion-based MST evaluation method

panel_info()

Extract Panel Structure from an MST Route Map

find_cut()

Find TIF-Crossing Cut Scores for MST Routing

plot(<find_cut>)

Plot TIF Curves and Cut Scores from a find_cut Result

run_mst()

Multistage-Adaptive Test (MST) Simulation

Data Simulation & Utilities

Simulate item response data and compute supporting quantities.

simdat()

Simulated Response Data

lwrc()

Lord-Wingersky Recursion Formula

gen.weight()

Generate Weights

covirt()

Asymptotic Variance-Covariance Matrices of Item Parameter Estimates

bind.fill()

Bind Fill

bisection()

The Bisection Method to Find a Root

summary()

Summary of Item Calibration Results

Importing External Software Output

Import item parameter estimates from IRT software output, write input files, and execute external programs from R.

bring.flexmirt() bring.bilog() bring.parscale() bring.mirt()

Import Item and Ability Parameters from IRT Software

run_flexmirt()

Run flexMIRT from Within R

write.flexmirt()

Write a "-prm.txt" File for flexMIRT

IRT Model Probability Functions

Core IRT model functions for computing item response probabilities.

drm()

Dichotomous Response Model (DRM) Probabilities

prm()

Polytomous Response Model (PRM) Probabilities (GRM and GPCM)

Datasets

Example datasets bundled with the package.

LSAT6

LSAT6 Data

simCAT_DC

Simulated Single-Item Format CAT Data

simCAT_MX

Simulated Mixed-Item Format CAT Data

simIPD

Simulated CAT Data for Item Parameter Drift (IPD) Detection

simMG

Simulated multiple-group data

simMST

Simulated 1-3-3 MST Panel Data