Bias and Linking Error in Fixed Item Parameter Calibration

The two-parameter logistic (2PL) item response theory (IRT) model is frequently applied to analyze group differences for multivariate binary random variables. The item parameters in the 2PL model are frequently fixed when estimating the mean and the standard deviation for a group of interest. This m...

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Main Author: Alexander Robitzsch
Format: Article
Language:English
Published: MDPI AG 2024-09-01
Series:AppliedMath
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Online Access:https://www.mdpi.com/2673-9909/4/3/63
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author Alexander Robitzsch
author_facet Alexander Robitzsch
author_sort Alexander Robitzsch
collection DOAJ
description The two-parameter logistic (2PL) item response theory (IRT) model is frequently applied to analyze group differences for multivariate binary random variables. The item parameters in the 2PL model are frequently fixed when estimating the mean and the standard deviation for a group of interest. This method is also called fixed item parameter calibration (FIPC). In this article, the bias and the linking error of the FIPC approach are analytically derived in the presence of random uniform differential item functioning (DIF). The adequacy of the analytical findings was validated in a simulation study. It turned out that the extent of the bias and the variance in distribution parameters increases with increasing variance of random DIF effects.
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spelling doaj-art-d71f0fe39be64647965a931362930f9d2025-08-20T01:55:57ZengMDPI AGAppliedMath2673-99092024-09-01431181119110.3390/appliedmath4030063Bias and Linking Error in Fixed Item Parameter CalibrationAlexander Robitzsch0IPN—Leibniz Institute for Science and Mathematics Education, Olshausenstraße 62, 24118 Kiel, GermanyThe two-parameter logistic (2PL) item response theory (IRT) model is frequently applied to analyze group differences for multivariate binary random variables. The item parameters in the 2PL model are frequently fixed when estimating the mean and the standard deviation for a group of interest. This method is also called fixed item parameter calibration (FIPC). In this article, the bias and the linking error of the FIPC approach are analytically derived in the presence of random uniform differential item functioning (DIF). The adequacy of the analytical findings was validated in a simulation study. It turned out that the extent of the bias and the variance in distribution parameters increases with increasing variance of random DIF effects.https://www.mdpi.com/2673-9909/4/3/63item response theory2PL modelbiaslinking errorfixed item parameter calibrationdifferential item functioning
spellingShingle Alexander Robitzsch
Bias and Linking Error in Fixed Item Parameter Calibration
AppliedMath
item response theory
2PL model
bias
linking error
fixed item parameter calibration
differential item functioning
title Bias and Linking Error in Fixed Item Parameter Calibration
title_full Bias and Linking Error in Fixed Item Parameter Calibration
title_fullStr Bias and Linking Error in Fixed Item Parameter Calibration
title_full_unstemmed Bias and Linking Error in Fixed Item Parameter Calibration
title_short Bias and Linking Error in Fixed Item Parameter Calibration
title_sort bias and linking error in fixed item parameter calibration
topic item response theory
2PL model
bias
linking error
fixed item parameter calibration
differential item functioning
url https://www.mdpi.com/2673-9909/4/3/63
work_keys_str_mv AT alexanderrobitzsch biasandlinkingerrorinfixeditemparametercalibration