## Classical Strength Theory

See DECISION-MAKING THEORIES.

CLASSICAL TEST and MEASUREMENT THEORY. In the speculative domain within psychological testing, classical test theory (also called classical measurement theory) is a statistical approach according to which a person's measured score is assumed to be equal to the true score plus random measurement error, where this error is assumed usually to have a mean of zero and is considered to be uncorrelated with the true score. This theoretical approach defines the "reliability" (internal consistency or stability) of a test item as the proportion of the total variance in scores that is due to variance in the true scores. The major alternative to classical test theory is the item response theory (also called latent trait theory) which is based on the assumption that the probability of a particular response to a test item is a joint function of one or more aspects of the respondent and one or more aspects of the test item itself. The concept of "item response function" defines the relationship of these parameters to the probability of a particular response, where values are estimated from the measurable responses of respondents to the test item. The Rasch Scale - named after the Danish psychometrician Georg Rasch (1901-1980) - is a psychometric application of item response theory and assumes, similarly, that the probability of a particular response to a test item depends on two independently estimated parameters: the extent to which the item elicits a "latent trait," and the status of the respondent on that trait which is constant across test items. See also MEASUREMENT THEORY; PROBABILITY THEORY AND LAWS. REFERENCES

Dunlap, J. W. (1938/1941). Recent advances in statistical theory and applications. American Journal of Psychology, 51, 558-571; 54, 583-601.

Rasch, G. (1960). Studies in mathematical psychology: I. Probabilistic models for some intelligence and attainment tests. Oxford, UK: Nielsen & Lyd-ische. Magnusson, D. (1966). Test theory. Reading, MA: Addison-Wesley. Nunnally, J. (1978). Psychometric theory.

New York: McGraw-Hill. Lord, F. M. (1980). Applications of item response theory to practical testing problems. Hillsdale, NJ: Erlbaum.

Aiken, L. R. (1982). Psychological testing and assessment. Boston: Allyn & Bacon.

CLASSICAL THEORIES OF INTELLIGENCE. See INTELLIGENCE, THE-ORY/ LAWS OF.

## Brain Training Improving Your Memory

For as much as we believe we train our brains and give them a good workout, we seldom actually do it on a regular basis. In most cases, our brains are not used in a balanced way. We're creatures of habit. We find a way to do things that we consider comfortable and we seldom change our ways.

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