Numerous studies have shown increasing item reliabilities as an effect of the item position in personality scales. Traditionally, these context effects are analyzed based on item-total correlations. This approach neglects that trends in item reliabilities can be caused either by an increase in true score variance or by a decrease in error…

Background: Relatively little is known about the genetic architecture of childhood behavioral disorders in very young children. Method: In this study, parents completed the Infant-Toddler Social and Emotional Assessment, a questionnaire that assesses symptoms of childhood disorders, as well as socio-emotional competencies, for 822 twin pairs…

Recently, there has been an increasing level of interest in reporting subscores. This paper examines the issue of reporting subscores at an aggregate level, especially at the level of institutions that the examinees belong to. A series of statistical analyses is suggested to determine when subscores at the institutional level have any added value…

One of the most difficult concepts for statistics students is the standard error of the mean. To improve understanding of this concept, 1 group of students used a hands-on procedure to sample from small populations representing either a true or false null hypothesis. The distribution of 120 sample means (n = 3) from each population had standard…

Schulz (2006) provides a different perspective on standard setting than that provided in Reckase (2006). He also suggests a modification to the bookmark procedure and some alternative models for errors in panelists' judgments than those provided by Reckase. This article provides a response to some of the points made by Schulz and reports some…

Studies suggest that enjoyment, perceived benefits and perceived barriers may be important mediators of physical activity. However, the psychometric properties of these scales have not been assessed using Rasch modeling. The purpose of this study was to use Rasch modeling to evaluate the properties of three scales commonly used in physical…

When a simple random sample of size n is employed to establish a classification rule for prediction of a polytomous variable by an independent variable, the best achievable rate of misclassification is higher than the corresponding best achievable rate if the conditional probability distribution is known for the predicted variable given the…

A procedure for checking the score equivalence of nearly identical editions of a test is described. The procedure employs the standard error of equating (SEE) and utilizes graphical representation of score conversion deviation from the identity function in standard error units. Two illustrations of the procedure involving Scholastic Aptitude Test…

The purpose of this study was to examine the effect of test dimensionality on the stability of examinee ability estimates and item response theory (IRT) based score reports. A simulation procedure based on W. F. Stout's Essential Unidimensionality was used to generate test data with one dominant trait for the whole test and three minor traits…

The use of a covariate for randomized response (RRT) research has been shown to reduce standard errors of sensitive trait proportion estimates. At the same time, the model has been shown to be subject to serious misspecification when the relationship between the covariate and the sensitive trait is non-monotonic. The RRT covariate model is adapted…

Logistic regression was used for modeling the observation-to-indicator ratio needed for the standard error scree procedure (SEscree) to correctly identify the number of factors existing in generated sample correlation matrices. The created correlation matrices were manipulated along the number of factors (4,6), sample size (250, 500), magnitude of…

Educational researchers often use multiple statistical tests in their research studies and program evaluations. When multiple statistical tests are conducted, the chance that Type I errors may be committed increases. Thus, the researchers are faced with the task of adjusting the alpha levels for their individual statistical tests in order to keep…

A probability distribution was developed for the Andrews-Pregibon (AP) statistic. The statistic, developed by D. F. Andrews and D. Pregibon (1978), identifies multivariate outliers. It is a ratio of the determinant of the data matrix with an observation deleted to the determinant of the entire data matrix. Although the AP statistic has been used…

Simulations were performed to verify the accuracy with which the Mantel-Haenszel (MH) and Rasch PROX procedures recover simulated item bias. Several standard error estimators for the MH procedure were evaluated. Item bias is recovered satisfactorily by both techniques under all simulated conditions. The proposed MH standard error estimators have…

A recurring problem in educational research is how to account for non-random selection that has restricted the range of the variables of interest in correlational analyses. Several expressions due to H. Pearson (1903) and presented in matrix notation by D. N. Lawley (1943-44) are commonly used in selection settings to adjust for samples chosen on…