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The Reliability Coefficient

Published online by Cambridge University Press:  01 January 2025

Truman L. Kelley*
Affiliation:
Harvard University

Abstract

The reliability coefficient is unlike other measures of correlation in that it is a quantitative statement of an act of judgment,—usually the test maker's, — that the things correlated are similar measures. Attempts to divorce it from this act of judgment are misdirected, just as would be an attempt to eliminate judgment of sameness of function of items when a test is originally drawn up. A “coefficient of cohesion,” entirely devoid of judgment, measuring the singleness of test function is proposed as an essential datum with reference to a test, but not as a substitute for the similar-form reliability co-efficient.

Type
Original Paper
Copyright
Copyright © 1942 The Psychometric Society

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References

* A simplified method of using scaled data for purposes of testing, School and Society, July 1 and 8, 1916, 4, nos. 79-80.

The reliability of test scores, J. Educ. Res., May 1921. Also, Note on the reliability of a test, J. Educ. Psych., Apr., 1924, 15, no. 4.

* G. F. Kuder and M. W. Richardson, The theory of the estimation of test reliability, Psychometrika, 1937, 2, 151-160.

* The calculation of test reliability coefficients based on the method of rational equivalence, J. educ. Psych. Dec., 1939, 30.

* Essential traits of mental life, 1935, and Talents and tasks, Harvard Education Papers No. 1, 1940.

* T. L. Kelley, When Cease Firing Sounds, Christian Science Monitor, Nov. 8. 1941, defined morale as “the individual attitude in a group endeavor,” following which the morale of a test item is the congruence of its intent (what it measures) with that of the group of items constituting the test.