In this article, we present the results of three question design experiments on inter-item correlations, which tested a grid design against a single-item design. The first and second experiments examined the inter-item correlations of a set with five and seven items, respectively, and the third experiment examined the impact of the question design…

The "Motor-Free Visual Perception Test-fourth edition" (MVPT-4) is a revised version of the "Motor-Free Visual Perception Test-third edition." The MVPT-4 is used to assess the visual-perceptual ability of individuals aged 4.0 through 80+ years via a series of visual-perceptual tasks that do not require a motor response. Test…

In order to initiate more research on the role of reading motivation during the initial stages of learning to comprehend texts, we developed the "Reading Motivation Questionnaire for Elementary Students" (RMQ-E). The sample comprised 1497 elementary students in Grades 1-3. By means of exploratory and confirmatory factor analyses, three…

Measurement error in dependent variables reduces the power of statistical tests to detect mean differences of specified magnitude. Procedures for determining power and sample size that consider the reliability of the dependent variable are discussed and illustrated. Methods for estimating reliability coefficients used in these procedures are…

Procedures are developed for testing the hypothesis that Cronbach's alpha reliability coefficient is equal for two tests given to the same subjects. (Author/JKS)

It is suggested that error of measurement cannot be routinely incorporated into the "error term" in statistical tests, and that the reliability of test scores does not have the simple relationship to statistical inference that one might expect. (Author/GK)

Reliability guides research design and is used as a standard for judging the credibility of findings and inferences. Using data gathered in a school health education curriculum evaluation as an example, possible errors in hypothesis testing are examined. Appropriateness of internal consistency as a measure of reliability is discussed and…

The objective of this paper is to examine the relationship between the unreliability of difference scores and the power of tests of significance in an attempt to determine the validity of the paradox for the measurement of change presented by Overall and Woodward: that the power of tests of significance is maximum when the reliability of the…

Textbook calculations of statistical power or sample size follow from formulas that assume that the variables under consideration are measured without error. However, in the real world of behavioral research, errors of measurement cannot be neglected. The determination of sample size is discussed, and an example illustrates blocking strategy.…

Eight different methods are reviewed for determining whether two or more tests are equivalent measures. These methods vary in restrictiveness from the Wilks-Votaw test of compound symmetry (which requires that all means, variances, and covariances are equal), to Joreskog's theory of congeneric tests (which requires only that the tests are measures…

The statistical properties of two methods of estimating gain scores for groups in quasi-experiments are compared: (1) gains in scores standardized separately for each group; and (2) analysis of covariance with estimated true pretest scores. The fan spread hypothesis is assumed for groups but not necessarily assumed for members of the groups.…