Policymakers and school administrators have embraced value-added models of teacher effectiveness as tools for educational improvement. Teacher value-added estimates may be viewed as complicated scores of a certain kind. This suggests using a test validation model to examine their reliability and validity. Validation begins with an interpretive…

Generalizability theory provides a technique for accurately estimating the reliability of measurements. The power of this theory is based on the simultaneous analysis of multiple sources of error variances. Equally important, generalizability theory considers relationships among the sources of measurement error. Just as multivariate inferential…

This paper discusses the benefits of using generalizabilty theory in lieu of classical test theory. Generalizability theory subsumes and extends the precepts of classical test theory by estimating the magnitude of multiple sources of measurement error and their interactions simultaneously in a single analysis. Since classical test theory examines…

Cross-validation, an economical method for assessing whether sample results will generalize, is discussed in this paper. Cross-validation is an invariance technique that uses two subsets of the data sample to derive discriminant function coefficients. The two sets of coefficients are then used with each data subset to derive discriminant function…

It is erroneous to extend or generalize the inter-rater reliability coefficient estimated from only a (small) proportion of the sample to the rest of the sample data where only one rater is used for scoring, although such generalization is often made implicitly in practice. It is shown that if inter-rater reliability estimate from part of a sample…

Previous studies have indicated that the reliability of test scores composed of testlets might be overestimated by conventional item-based reliability estimation methods (R. Thorndike, 1953; A. Anastasi, 1988; S. Sireci, D. Thissen, and H. Wainer, 1991; H. Wainer and D. Thissen, 1996). This study used generalizability theory to investigate the…

Multivariate methods are being used with increasing frequency in educational research because these methods control "experimentwise" error rate inflation, and because the methods best honor the nature of the reality to which the researcher wishes to generalize. This paper: explains the basic logic of canonical analysis; illustrates that…

Generalizability or invariance procedures have been known for over three decades. Through the years, these procedures have not been widely discussed or employed. One reason for the lack of use is that most of the articles on invariance procedures have been mathematically oriented. The mathematical orientation of research articles and the lack of…

Applied psychologists who provide services in nations composed of multiple and varied cultural groups face certain ethical dilemmas that would not arise in more homogeneous societies. These ethical dilemmas revolve around the concept of population validity. Population validity refers to the generalizability of research findings across different…

Three procedures for evaluating the sampling specificity of results are reviewed. These procedures are Tukey's jacknife technique, Efron's bootstrap technique, and cross-validation methods. The jacknife technique uses different subsamples derived from the original total data set to provide empirical estimates of the generalizability of effect…

Evaluated Angoff ratings from eight different occupational licensing examinations through generalizability theory to estimate the optimal number of raters. Results indicate that approximately 10 to 15 raters is an optimal target range. (SLD)

Arguments are presented for conceptualizing validity within a postmodern approach. Validity, reliability, and generalizability have been a holy trinity of social science research, and standard definitions of validity have been taken from criteria developed for psychometric tests. From a postmodern point of view, validity is sometimes discarded as…

Generalizability or invariance procedures have been known for over three decades. Through the years, these procedures have not been widely discussed or employed. One reason for the lack of use is that most of the articles on invariance procedures have been mathematically oriented. The mathematical orientation of research articles and the lack of…

It is incorrect to say "the test is reliable" because reliability is a function not only of the test itself, but of many factors. The present paper explains how different factors affect classical reliability estimates such as test-retest, interrater, internal consistency, and equivalent forms coefficients. Furthermore, the limits of classical test…

Unstable, and potentially invalid, variance component estimates may result from using only a limited portion of available data from operational performance assessments. However, missing observations are common in these settings because of the nature of the assessment design. This paper describes a procedure for overcoming the computational and…