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ltm (version 1.1-0)

Latent Trait Models under IRT

Description

Analysis of multivariate dichotomous and polytomous data using latent trait models under the Item Response Theory approach. It includes the Rasch, the Two-Parameter Logistic, the Birnbaum's Three-Parameter, the Graded Response, and the Generalized Partial Credit Models.

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Install

install.packages('ltm')

Monthly Downloads

10,183

Version

1.1-0

License

GPL (>= 2)

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Last Published

September 11th, 2017

Functions in ltm (1.1-0)

biserial.cor

Point-Biserial Correlation
coef

Extract Estimated Loadings
anova

Anova method for fitted IRT models
Mobility

Women's Mobility
Science

Attitude to Science and Technology
GoF

Goodness of Fit for Rasch Models
LSAT

The Law School Admission Test (LSAT), Section VI
Abortion

Attitude Towards Abortion
Environment

Attitude to the Environment
WIRS

Workplace Industrial Relation Survey Data
gh

Gauss-Hermite Quadrature Points
gpcm

Generalized Partial Credit Model - Polytomous IRT
cronbach.alpha

Cronbach's alpha
descript

Descriptive Statistics
grm

Graded Response Model - Polytomous IRT
information

Area under the Test or Item Information Curves
mult.choice

Multiple Choice Items to Binary Responses
person.fit

Person-Fit Statistics and P-values
factor.scores

Factor Scores - Ability Estimates
fitted

Fitted Values for IRT model
plot IRT

Plot method for fitted IRT models
ltm

Latent Trait Model - Latent Variable Model for Binary Data
margins

Fit of the model on the margins
rmvlogis

Generate Random Responses Patterns under Dichotomous and Polytomous IRT models
summary

Summary method for fitted IRT models
plot descript

Descriptive Statistics Plot method
testEquatingData

Prepares Data for Test Equating
tpm

Birnbaum's Three Parameter Model
item.fit

Item-Fit Statistics and P-values
ltm-package

Latent Trait Models for Item Response Theory Analyses
plot fscores

Factor Scores - Ability Estimates Plot method
rasch

Rasch Model
unidimTest

Unidimensionality Check using Modified Parallel Analysis
vcov

vcov method for fitted IRT models
rcor.test

Pairwise Associations between Items using a Correlation Coefficient
residuals

Residuals for IRT models