The Importance Of Classical Test Theory

Classical Test Theory (CTT) is a theory of measurement that defines the conceptual foundation of reliability and delineates methods to estimate the reliability of psychological measures (Furr & Bacharach, 2014). According to the CTT, reliability stems from observed scores, true scores, and measurement error. True scores are defined as the actual or real level of the psychological attribute being measured by a test (103) or the scores obtained if a test was not affected by measurement error. Measurement error (or error) is defined as the extent to which other characteristics unrelated to the target construct contribute to differences in observed scores; error creates inconsistency between observed and true scores. Error can affect psychological …show more content…
They approached construct validation in test interpretation as a measure of some attribute or quality, which is not operationally defined (282). Construct validity has traditionally been operationalized as a statistic known as the validity coefficient (r), which is a statement of the proportion of the test score variance that is attributable to the construct variable (289). Bornstein problematizes this conceptualization of validity by claiming that a test score is valid for anything with which it correlates when validity is equated with magnitude of predictor-criterion association (Bornstein, …show more content…
Messick believes that the heart of validity lies within the meaning the test scores rather than considering validity as a property of the test. According to Messick, an important form of validity evidence bears on the social consequences of test interpretation and use. To compare this concept to Cronbach and Meehl’s (1955) approach on construct validity, Messick explains that unintended consequences of test interpretation are part of the construct’s nomological network that must be taken into account in construct theory, score interpretation, and test use