Differential Functioning of Items and Tests


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Documentation for package ‘DFIT’ version 1.0-3

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DFIT-package Differential Functioning of Items and Tests framework
Ase1pl Calculates the asymptotic variance for difficulty parameter estimates under the 1pl model
Ase2pl Calculates the asymptotic covariance matrix of item parameter estimates under the 2pl model
Ase3pl Calculates the asymptotic covariance matrix of item parameter estimates under the 3pl model
AseIrt Calculates the asymptotic covariance matrices for item parameters according with the IRT model.
Bound3PlIpr Takes item parameters frp, Ipr and forces guessing to lie between 0 and 1
Calculate1plProb Calculates the item success probability under the 1PL model.
Calculate2plProb Calculates the item success probability under the 2PL model.
Calculate3plProb Calculates the item success probability under the 3PL model.
CalculateGrmExp Calculates the expected item score under the GRM model.
CalculateItemDifferences Calculates the differences between two item option characteristic curves for all options (minus one).
CalculatePcmExp Calculates the expected item score under the (G)PCM model.
Cdif Calculates CDIF index for an item with given item parameters of focal and reference groups.
CrossedProbabilities Calculates the crossed probabilities associated with the numerator and denominator of the odds-ratio under dichotomous IRT models
CutoffIpr Cut-off points for Ipr generated estimates
DeltaMhIrt Obtains the ETS Delta measure for Mantel-Haneszel DIF statistic effect size.
DFIT Differential Functioning of Items and Tests framework
dichotomousItemParameters Sets of focal and reference item parameters from Wright (2011).
Dtf Calculates DTF index for a set of items with given item parameters of focal and reference groups.
Ipr Item parameter replication
IprMh Mantel Haenszel for Item parameter replication
IprNcdif NCDIF for Item parameter replication
IprSam Signed Area Measure for Item parameter replication
IprUam Unsigned Area Measure for Item parameter replication
IrtMh Calculates the Mantel-Haenszel theoretical parameter when a dichotomous IRT model holds
Ncdif Calculates NCDIF index for an item with given item parameters of focal and reference groups.
PlotNcdif Plot the item characteristic (expected score) curve for focal and reference groups for the iiItem along with a representation of the focal group density.
polytomousItemParameters Sets of focal and reference item parameters from Raju et al. (2009)
ProductProbabilities Calculates the product of item response probabilities for dichotomous IRT models
SignedArea Calculates Raju's Signed Area Measure index for an item with given item parameters of focal and reference groups.
UnsignedArea Calculates Raju's Unsigned Area Measure index for an item with given item parameters of focal and reference groups.