As with several other human endeavors, psychology has tests and measurements which are essential in the assessment of various emotional and behavioral conditions with the objective of determining appropriate remedies. There are several psychological tests and measurements used in solving psycho-social problems currently employed by specialists in the field of psychology.
Q1: Describe the Components of True Score Theory
The true score theory as used in psychological testing is composed of two parts, which determine the ultimate score. The first element refers to the actual amount of whatever psychological variable being measured. It can be intellectual ability as measured in an intellectual test or the level of depression on the depression scale. The other part consists of a random error of measurement whose value is uncertain. The random error is influenced by factors such as the type of questions selected for the test, the particular time of the day the measurement was done or the inefficiencies of the materials used in the test. All such external variables affect those taking the tests differently depending on their personalities and traits. The true score of each test participant will therefore for be different. An exact score can, therefore, be termed as that average score obtained if an individual was to take part in a test for an infinite number of times. Alternatively, the true score refers to the residual score once the random error has been subtracted.
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Q2: Describe What Generalizability Theory Attempts to Do
According to Cronbach et. al. (1972), generalizability theory, commonly referred to as G theory, is a statistical theory that is used in the assessment of the reliability of behavioral measurements. G theory was conceived upon the realization that the undifferentiated error in true score theory gave a poor definition of the potential sources of measurement error. G theory is therefore, designed primarily to isolate and estimate as many facets of measurement error as is reasonably viable. The study consists of important facets over which decision makers can make generalizations. The facets may include items, forms, occasions and raters on all levels. The facets including all their levels constitute the universe of generalization over which the decision makers may want to make generalizations. Essentially, the decision maker specifies the universe of generalization after which he breaks down an observed measurement into a component for the universe score and one or more error components with information collected in a G study.
Q3: Compare t he “Standard” a nd “Refined” Definitions o f Test Validity .
There are distinct differences between the standard and the refined definitions of validity. The standard definition concentrates on the outcome of the measure without considering the potential constituents of the observed score. It is, therefore, essential to point out that there are three factors that should be outlined before conducting reliable tests; the type of measure, population involved and purpose of the measure. Failure to consider these factors will render the results unreliable. As such, content validity is emphasized to ensure that empirical results are obtained. The refined definition of validity, therefore, accounts for all the facets that influence the measurement score. This helps to assign numerical values in our ordinary observation and increase precision in all the measurements. Refined definitions of validity, therefore, use diverse methods aimed at eliminating extraneous errors associated with the conditions surrounding the tests.
Q5: Identify t he Three Traditional Categories f or Describing Validity Evidence
The traditional categories for describing validity were based on criteria, content, and construct. According to criterion validity evidence, the test scores are systematically related to one or more criteria outcome. The future performance is anticipated based on the current measurement score; hence, drawing a correlation among the different criteria. Content-related validity evidence proposes that the content of the test task is logically related to the behavior content. It is often assessed based on the procedures and plans used in the test construction. Finally, the construct validity evidence refers to the extent to which the test measures a planned hypothetical construct. It was always used by psychologists to measure abstract attributes.
Cronbach, L. J., Gleser, G. C., Nanda, H., & Rajaratnam, N. (1972). The Dependability of Behavioral Measurements . New York, NY: Wiley.
Cronbach, L., 1990. Essentials of psychological testing. New York, NY: Harper & Row Press
Carmines, E., and Zeller, R., 1979. Reliability and Validity Assessment . Beverly Hills, CA: Sage Publications