Explores effects of ignoring one or more levels of variation in hierarchical linear regression analysis, using a model with four hierarchical levels. Ignoring the top or intermediate levels influences fixed coefficients, variance components, and their corresponding standard error and can lead to different research conclusions. (Contains 16…

A program for obtaining ability estimates and their standard errors under a variety of psychometric models is documented. The general models considered are (1) classical test theory; (2) item factor analysis for continuous censored responses; and (3) unidimensional and multidimensional item response theory graded response models. (SLD)

This activity makes students a part of an investigation that determines the frequency of a particular plant variety in a simulated population. Provides an opportunity for students to observe the inherent variability of estimates, observe the relationship between sample size and sampling error, and consider aspects of research design. (Author/SAH)

The calculations of D. Schretlen, R. H. B. Benedict, and J. H. Bobholz for the reliabilities of a short form of the Wechsler Adult Intelligence Scale--Revised (WAIS-R) (1994) consistently overestimated the values. More accurate values are provided for the WAIS--R and a seven-subtest short form. (SLD)

Because of the requirement of reporting effect sizes and in the interest of measurement of change within the item response theory framework, their combination becomes a new issue. In the present study, repeated measures are decomposed as an initial ability and one or more modifiabilities (gain score) using a multidimensional Rasch model. The…

This article considers the implications for other noncentrality parameter-based statistics from Steiger's (1998) multiple sample adjustment to the root mean square error of approximation (RMSEA) measure. When a structural equation model is fitted simultaneously in more than 1 sample, it is shown that the calculation of the noncentrality parameter…

The primary purpose of this article was to offer a methodological critique in support of arguments that racial categories should be replaced as explanatory constructs in psychological research and theory. To accomplish this goal, the authors (a) summarized arguments for why racial categories should be replaced; (b) used principles of the…

The concept of error detection plays a central role in theories of executive control. In this article, the authors present a mechanism that can rapidly detect errors in speeded response time tasks. This error monitor assigns values to the output of cognitive processes involved in stimulus categorization and response generation and detects errors…

Educational and psychological testing textbooks typically warn of the inappropriateness of performing arithmetic operations and statistical analysis on percentiles instead of raw scores. This seems inconsistent with the well-established finding that transforming scores to ranks and using nonparametric methods often improves the validity and power…

The main purpose of this study is to examine the content structure of the Multistate Bar Examination (MBE) using the "table of specifications" model from the perspective of multivariate generalizability theory. Specifically, using MBE data collected over different years (six administrations: three from the February test and three from July test),…

Item bias is a major threat to measurement validity. Methods for detecting differential item functioning (DIF) are now commonly used to identify potentially biased items. DIF detection methods for dichotomous items are well developed, but those for ordinal items are less well developed. In this article, the authors compare four methods for…

Coefficient alpha, the most commonly used estimate of internal consistency, is often considered a lower bound estimate of reliability, though the extent of its underestimation is not typically known. Many researchers are unaware that coefficient alpha is based on the essentially tau-equivalent measurement model. It is the violation of the…

This article examines the intersection of psychometrics and sociolinguists in the testing of English language learners (ELLs); it discusses language, dialect, and register as sources of measurement error. Research findings show that the dialect of the language in which students are tested (e.g., local or standard English) is as important as…

The relationship between intelligence and personality has been of scientific interest for over 100 years. However, most contemporary estimates of these relationships are limited because they do not separate the variance due to general and narrow cognitive abilities. This study demonstrates that this methodological oversight can distort estimates…

A statistical test for detecting answer copying on multiple-choice tests based on Cohen's kappa is proposed. The test is free of any assumptions on the response processes of the examinees suspected of copying and having served as the source, except for the usual assumption that these processes are probabilistic. Because the asymptotic null and…