Perluasan Mengenai Koefisien Realibilitas dari Kuder-Richardson (KR-20)
Sunardi Wirjosudirdjo
Abstract. The internal consistency of a test is usually measured by using Kuder-Richardson’s formula called KR-20, i.e. equation (1). It is clear that formula (1) is only applicable to the case where the score of each item is 0 or 1. If the score of each item is not 0 or 1, then (1) can be written as equation (2). Where si is the standard deviation of the ith item. Furthermore, formula (1) or (2) is applicable for the case where the test is designed so that the items in the test intended to be homogeneous. If the items of the test are not intended to be homogeneous, then we can use weighting so that r becomes maximum. It happens that the weight ai of the ith item should satisfy so that ai si is the ith component of the characteristic vector correspond to the greatest eigenvalue of the correlation matrix between items. If the correlation coefficients between item are positive then the ai's are positive and unique.
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