Modified Robust Z method for equating and detecting item parameter drift

A Modified Frequency Estimation Equating Method for the Common- Item Non-Equivalent Groups Design

Frequency estimation (also called post-stratification) is an equating method employed under the common-item nonequivalent groups design. A modified frequency estimation method is proposed here, based on altering one of the traditional assumptions in frequency estimation in order to correct for equating bias. A simulation study was carried out to compare equating errors for the modified frequenc...

Longitudinal Effects of Item Parameter Drift

Robust Drift Parameter Estimation In Diffusion Processes

We consider some inference problems concerning the drift parameters vector of diffusion process. Namely, we consider the case where the parameters vector is suspected to satisfy certain restriction. Under such a design and imprecise prior information, we propose Stein-rule (or shrinkage) estimators which improves over the performance of the classical maximum likelihood estimator (MLE). By using...

Investigating the Impact of Item Parameter Drift for Item Response Theory Models with Mixture Distributions

This study investigates the impact of item parameter drift (IPD) on parameter and ability estimation when the underlying measurement model fits a mixture distribution, thereby violating the item invariance property of unidimensional item response theory (IRT) models. An empirical study was conducted to demonstrate the occurrence of both IPD and an underlying mixture distribution using real-worl...

Selection the best Method of Equating Using Anchor-Test Design‎ in Item Response Theory ‎‎

Explaining the problem. The equating process is used to compare the scores of the two different tests with the same theme‎. ‎The goal of this research is finding the best method of equating data using Logistic model. ‎ Method. we are using the data of Ph.D‎. ‎test in Statistic major for two consecutive years 92 and 93‎. ‎For analyzing‎, ‎we are specifically using the tests of Statistics major ...