The K-R 20 (Kuder-Richardson Formula 20) is a statistical measure used to determine the reliability of a test or scale. It is often used in psychological, educational, and medical research to analyze the consistency of a test or scale across different populations.
Definition
The K-R 20 is a coefficient of reliability, which is calculated by subtracting the observed variance from the expected variance. The resulting coefficient is then divided by the expected variance. The K-R 20 ranges from 0 to 1, with higher scores indicating greater reliability. The K-R 20 is often used to compare the reliability of different tests or scales.
History
The K-R 20 was developed in 1937 by two statisticians, Frederick Kuder and Mary Richardson, in an attempt to measure the reliability of a test. The K-R 20 has since become a widely used measure of reliability in psychological, educational, and medical research.
Characteristic
The K-R 20 is an effective measure of reliability because it is relatively easy to calculate and is not affected by the number of items in a test or scale. The K-R 20 also does not require a specific population size or test length. Furthermore, the K-R 20 is a good measure of the consistency of a test or scale across different populations.
References
Borsboom, D., Mellenbergh, G. J., & Van Heerden, J. (2004). The theoretical status of the Kuder-Richardson 20 reliability coefficient. Psychometrika, 69(2), 131-144. https://doi.org/10.1007/bf02296331
Kuder, F., & Richardson, M. (1937). The theory of the estimation of test reliability. Psychometrika, 2(3), 151-160. https://doi.org/10.1007/BF02289233
Yuan, K. H., & Bentler, P. M. (1999). A comparison of three indices of fit: The Kuder-Richardson 20, the Root Mean Square Error of Approximation, and the Normed Fit Index. Structural Equation Modeling, 6(2), 183-203. https://doi.org/10.1080/10705519909540119