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…

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…

When accurately assigned and administered appropriately, testing accommodations help ameliorate the effects of personal characteristics that limit access to critical information and prevent a person from demonstrating his or her true abilities in the tested domain. Inaccurate assignment or misuse of accommodations may counteract the benefits of…

In this study the authors investigated the use of 5 (i.e., Claudy, Ezekiel, Olkin-Pratt, Pratt, and Smith) R[squared] correction formulas with the Pearson r[squared]. The authors estimated adjustment bias and precision under 6 x 3 x 6 conditions (i.e., population [rho] values of 0.0, 0.1, 0.3, 0.5, 0.7, and 0.9; population shapes normal, skewness…

New Leaders for New Schools, a non-profit organization committed to training high-quality urban public school principals, received grants from the U.S. Department of Education in 2006 and 2007 to support the development of innovative teacher compensation strategies. New Leaders is partnering with four urban school districts and a consortium of…

Large scale surveys usually employ a complex sampling design and as a consequence, no standard methods for estimation of the standard errors associated with the estimates of population means are available. Resampling methods, such as jackknife or bootstrap, are often used, with reference to their properties of robustness and reduction of bias. A…

A Monte Carlo study was used to examine the Type I error rates of five multivariate tests for the single-factor repeated measures model. The performance of Hotelling's T-squared and four nonparametric tests, including a chi-square and an "F" test version of a rank-transform procedure, was investigated for different distributions, sample…

A person's obtained score on a test provides an estimate of the individual's "true" score on that test. The obtained score is considered to have two parts, the true component and the error component. Classical test theory assumes that obtained scores for an individual over multiple administrations of the same test will lie symmetrically…

Stepwise regression is not an adequate technique to provide the best set of variables with which to predict the dependent variable. By using the stepwise regression method, one who attempts to select the best set of predictors of a given dependent variable will face more problems than he or she attempted to resolve. This is illustrated with an…

This study examined the robustness of the estimation of fixed-effects in multilevel analysis, as might occur in the conduct of school-effects studies with outlying schools. Outlying values for both intercepts and slopes for individual schools were modeled separately to determine the effects of extreme values of second-level variables on the…

Norm-referenced tests yield information regarding a student's performance in comparison to a norm or average of performance by similar students. Norms are statistics that describe the test performance of a well-defined population. The process of constructing norms, called norming, is explored briefly in this paper. Some of the most widely reported…

The Job Satisfaction Survey (JSS) (P. Spector, 1985 and 1992) is a 36-item survey instrument designed to measure 9 aspects of job satisfaction, including: (1) pay; (2) promotion; (3) supervision; (4) benefits; (5) contingent rewards; (6) operating procedures; (7) co-workers; (8) nature of work; and (9) communication. In addition to measuring the…

Item response theory (IRT) model parameter estimates have considerable merit and open up new directions for test development, but misleading results are often obtained because of errors in the item parameter estimates. The problem of the effects of item parameter estimation errors on the test development process is discussed, and the seriousness…

Statistics used to estimate the population correlation ratio were reviewed and evaluated. The sampling distributions of Kelly's and Hays' statistics were studied empirically by computer simulation within the context of a three level one-way fixed effects analysis of variance design. (Author/RC)

Some basic statistical concepts relevant to the teacher--mean scores, standard deviation, normal and skewed distributions, z scores, item analysis, standard error of measurement, reliability--and their use by the teacher are explained. (RM)