What is the main purpose of using the KR-20 coefficient?

The KR-20 coefficient, also known as Kuder-Richardson Formula 20, is primarily used to assess the internal consistency or homogeneity of a test that consists of binary (dichotomous) items, such as true/false or yes/no questions. Internal consistency refers to the extent to which all parts of a test contribute equally to what is being measured. When a test is homogenous, it means that all its items are measuring the same underlying construct.

Using the KR-20 coefficient, researchers can quantify the degree to which different items on a test yield consistent results. A higher KR-20 value indicates greater internal consistency among the test items, suggesting that they are measuring the same construct effectively. This is crucial for ensuring that the test is reliable and can produce valid inferences about the subject being measured.

While the other options refer to different aspects of measurement reliability, none pertain directly to the primary function of the KR-20. For instance, estimating stability refers to test-retest reliability, which concerns the consistency of scores over time, while evaluating equivalence deals with how well different forms of a test correlate with one another. Measuring interrater reliability involves assessing the consistency of results when different raters score the same test