This paper compares three methods of item calibration--concurrent calibration, separate calibration with linking, and fixed item parameter calibration--that are frequently used for linking item parameters to a base scale. Concurrent and separate calibrations were implemented using BILOG-MG. The Stocking and Lord (1983) characteristic curve method…

Developed an empirical Bayes enhancement to Mantel-Haenszel (MH) analysis of differential item functioning (DIF) in which it is assumed that the MH statistics are normally distributed and that the prior distribution of underlying DIF parameters is also normal. (Author/SLD)

Dichotomous item response theory (IRT) models can be viewed as families of stochastically ordered distributions of responses to test items. This paper explores several properties of such distributions, especially those related to transfer to other distributions. Results are formulated as a series of theorems and corollaries that apply to…

Proposes a marginal Bayesian estimation procedure to improve item parameter estimates for the three parameter logistic model. Computer simulation suggests that implementing the marginal Bayesian estimation algorithm with four-parameter beta prior distributions and then updating the priors with empirical means of updated intermediate estimates can…

Previous studies that investigated the effect of unequal ability distributions on the Type I error (TIE) of the Mantel-Haenszel chi-square test for detecting differential item functioning (DIF) simulated ability distributions that differed only in means. This simulation study suggests that the magnitude of TIE inflation is increased, and the type…

Examined the degree to which coefficient alpha is affected by including items with different distribution shapes within a unidimensional scale. Computer simulation results indicate that reliability does not increase dramatically as a result of using differentially shaped items within a scale. Discusses implications for test construction. (SLD)

This paper evaluated multidimensional linking procedures with which multidimensional test data from two separate calibrations were put on a common scale. Data were simulated with known ability distributions varying on two factors which made linking necessary: mean vector differences and variance-covariance (v-c) matrix differences. After the…

To satisfy the security requirements of computerized adaptive tests (CATs), efforts have been made to control the exposure rates of optimal items directly by incorporating statistical methods into the item selection procedure. Since differences are likely to occur between the exposure control parameter derivation stage and the operational CAT…

Using the characteristic curve method for dichotomously scored test items, the sampling distributions of equating coefficients were examined. Simulations indicate that for the equating conditions studied, the sampling distributions of the equating coefficients appear to have acceptable characteristics, suggesting confidence in the values obtained…

A simple approximation to the conditional distribution of goodness-of-fit statistics for the Rasch model is presented that is used when item difficulties are known. The approximation, which is easily programmed, gives relatively accurate assessments of conditional p-values for tests of 10 or more items. (Author/SLD)

Examined five Rasch-model-based item-fit indices in terms of their distributional properties and the power of detecting item bias or differential item functioning. Results indicate that, although these five standardized item-fit indices did not depart significantly from a normal distribution, the Type I error rates were not reasonable. (Author/SLD)

The effects of skewed theta distributions on indices of differential item functioning (DIF) were studied, comparing Mantel Haenszel (N. Mantel and W. Haenszel, 1959) and DFIT (N. S. Raju, W. J. van der Linden, and P. F. Fleer) (noncompensatory DIF). The significance of the study is that in educational and psychological data, the distributions one…

A method is presented for estimating the accuracy and consistency of classifications based on test scores. The reliability of the score is used to estimate effective test length in terms of discrete items. The true-score distribution is estimated by fitting a four-parameter beta model. (SLD)

The delta method was used to derive standard errors (SES) of the Levine observed score and Levine true score linear test equating methods using data from two test forms. SES derived without the normality assumption and bootstrap SES were very close. The situation with skewed score distributions is also discussed. (SLD)

The Mantel-Haenszel (MH) procedure has become one of the most popular procedures for detecting differential item functioning (DIF). One of the most troublesome criticisms of this procedure is that while detection rates for uniform DIF are very good, the procedure is not sensitive to non-uniform DIF. In this study, examinee responses were generated…