When the internal consistency of a test is being determined on the basis of the Kuder-Richardson formula (KR21), then it should NOT be followed by
A) any attempts to determine predictive validity
B) any attempts to determine concurrent validity
C) the Spearman-Brown prophecy formula
D) none of these, since the KR21 is NOT an internal consistency measure

Question

Quizplus · Accepted Answer

The Spearman-Brown prophecy formula is used to estimate the reliability of a test when its length is changed (i.e. split-half reliability). However, KR21 is specifically designed for measuring internal consistency reliability for tests of dichotomously scored items. Therefore, the Spearman-Brown formula is not appropriate in this context. A and B are incorrect because determining predictive or concurrent validity is independent of determining internal consistency reliability using KR21. D is incorrect because KR21 is a commonly used internal consistency measure.

When the Internal Consistency of a Test Is Being Determined