What attribute does the KR-20 coefficient assess in dichotomous instruments?

The KR-20 coefficient is specifically designed to assess the homogeneity of items within a dichotomous measurement tool, such as a test or questionnaire with binary response options (e.g., yes/no, true/false). Homogeneity refers to the extent to which multiple items in a test measure the same underlying construct or trait.

When using the KR-20, researchers examine whether all items on a scale consistently reflect the same concept, ensuring that the different questions or statements yield similar results for individuals who share the same level of the trait being measured. A higher KR-20 value indicates greater homogeneity, meaning that the items function well together as a cohesive measurement of the intended construct.

This coefficient is particularly valuable in the context of reliability, which focuses on the consistency and stability of a measurement tool over time or across different contexts. However, the KR-20 explicitly measures homogeneity rather than overall reliability, which encompasses various aspects, including stability and internal consistency. This distinction helps clarify that while the KR-20 can inform reliability, it is grounded in assessing the uniformity of items in a dichotomous scale.