ACT reporting categories and ACT Readiness Ranges are new features added to the ACT score reports starting in fall 2016. For each reporting category, the number correct score, the maximum points possible, the percent correct, and the ACT Readiness Range, along with an indicator of whether the reporting category score falls within the Readiness…

Given the potential value of reliability generalization (RG) studies in the development of cumulative psychometric knowledge, the purpose of this paper is to provide a tutorial on how to conduct such studies and to serve as a guide for researchers wishing to use this methodology. After some brief comments on classical test theory, the paper…

This digest discusses sources of error in testing, several approaches to estimating reliability, and several ways to increase test reliability. Reliability has been defined in different ways by different authors, but the best way to look at reliability may be the extent to which measurements resulting from a test are characteristics of those being…

Although often ignored, reliability is critical when interpreting study effects and test results. Accordingly, this article focuses on the most commonly used estimate of reliability, internal consistency coefficients, with emphasis on coefficient alpha. An interpretive framework is provided for applied researchers and others seeking a conceptual…

This paper presents a method for estimating the accuracy and consistency of classifications based on test scores. The scores can be produced by any scoring method, including the formation of a weighted composite. The estimates use data from a single form. The reliability of the score is used to estimate its effective test length in terms of…

The standard error of measurement as a means for estimating the margin of error that should be allowed for in test scores is discussed. The true score measures the performance that is characteristic of the person tested; the variations, plus and minus, around the true score describe a characteristic of the test. When the standard deviation is used…

Through the standard error, rather than a reliability coefficient, generalizability theory provides an indicator of the uncertainty attached to school and individual scores on performance assessments. Recommendations are made to apply generalizability theory to current performance assessments, emphasizing practices that differ from usual…

Two sources of inconsistency were separated by reanalyzing data from a major study on short-term consistency. Little evidence was found for generalizability or behavioral predictability. Results supported the assumption that measurement error from short-term fluctuations is not due to systematic individual differences in response consistency.…