The unconditional--simultaneous--maximum likelihood (UML) estimation procedure for the one-parameter logistic model produces biased estimators. The UML method is inconsistent and is not a good alternative to conditional maximum likelihood method, at least with small numbers of items. The minimum Chi-square estimation procedure produces unbiased…

Effectiveness of jackknife methods in reducing bias in estimation of the log-1 autocorrelation parameter p1 was evaluated through a Monte Carlo study using sample sizes ranging from 6 to 500. These estimates appear less biased in the small sample case than many that have been investigated recently. (SLD)

A simulation study by B. D. Wright and G. A. Douglas is critiqued, which indicates that the unconditional maximum likelihood method is an appropriate substitute for the theoretically superior conditional method for estimating parameters of the Rasch model. The study appears to rest on inadequate logic. (TJH)

The predicted scores produced by regression with (1) single best predictor, (2) two best predictors, (3) all predictors with observed values, and (4) all predictors with or without observed values were compared with variable means as estimates of missing values. The study was conducted in a simulation mode on nx8 data matrices using various levels…

The purpose of this study was to assess the effects of correlated dimensions and differential ability on one dimension on parameter estimation when using a two-dimensional item response theory model. Multidimensional analysis of simulated two-dimensional item response data fitting the M2PL model of M. D. Reckase (1985, 1986) was conducted using…

The distinction between deterministic and statistical reasoning in the application of models to educational measurement is explicated. Issues addressed include the relationship between data and estimation equations, distinction between parameters and parameter estimates, and power of tests of fit of responses across the ability continuum. (TJH)

Some effects of using unidimensional item response theory (IRT) were examined when the assumption of unidimensionality was violated. Adaptive and nonadaptive tests were used. It appears that use of a unidimensional model can bias parameter estimation, adaptive item selection, and ability estimation for the two types of testing. (TJH)

The effect that collapsing ordered polytomous variable scales has on structural equation measurement model parameter estimates was examined. Four parameter estimation procedures were investigated in a Monte Carlo study. Collapsing categories in ordered polytomous variables had little effect when latent projection procedures were used. (SLD)

Four experiments involving 180 undergraduates evaluated the effectiveness of computer graphics in improving estimates for algebra word problems. Variations in the simulation resulted in successful and unsuccessful programs as measured by the frequency with which students improved their estimates. Quality of feedback to students while learning is…

The effects of correlated dimensions on parameter estimation were assessed, using a two-dimensional item response theory model. Past research has shown the inadequacies of the unidimensional analysis of multidimensional item response data. However, few studies have reported multidimensional analysis of multidimensional data, and, in those using…

Monte Carlo studies explored the sampling characteristics of Cohen's d and three approximations to Cohen's d when used as average effect size measures in meta-analysis. Reviews of 10, 100, and 500 studies (M) were simulated, with degrees of freedom (df) varied in seven steps from 8 to 58. In a two independent groups design, samples were obtained…

The impact of misspecification on the estimation, testing, and improvement of structural equation models was assessed via a population study in which a prototypical latent variable model was misspecified. Results provide insights into the maximum likelihood estimator versus a limited two-stage least squares estimator in LISREL. (TJH)

The present simulation study confirms that the corrected epsilon approximate test of B. Lecoutre yields a less biased estimation of population epsilon and reduces Type I error rates when compared to the epsilon approximate test of H. Huynh and L. S. Feldt. (SLD)

A Monte Carlo study, which simulated 10,000 examinees' responses to four tests, investigated the effect of item stratification on parameter estimation in multiple matrix sampling of achievement data. Practical multiple matrix sampling is based on item stratification by item discrimination and a sampling plan with moderate number of subtests. (SLD)

Simulation studies (N=4,000 simulees) examined the effect of misspecification of the latent ability distribution (theta) on the accuracy and efficiency of marginal maximum likelihood (MML) item parameter estimates and on MML statistics to test sufficiency and conditional independence. Results were compared to those of the conditional maximum…