Examination for Professional Practice of Psychology (EPPP) 2025 – 400 Free Practice Questions to Pass the Exam

Reliability is a critical aspect of psychological testing because it refers to the consistency and stability of test scores across different occasions or different forms of the test. When a psychological test is reliable, it produces similar results under consistent conditions, meaning that if a person takes the same test multiple times, they should receive comparable scores, assuming their traits or abilities have not changed. This consistency is essential for interpreting test results accurately and for making decisions based on those results, such as in clinical, educational, or organizational settings.

High reliability enhances the trustworthiness of a test, making it possible to measure psychological constructs with confidence. Without reliability, any observed score may be seen as subject to random error, which undermines the validity and usefulness of the test outcomes.

While aspects like norms, validity, and standardization are also important in psychological testing, they serve different purposes. Norms provide a reference point for interpreting scores, validity ensures that the test measures what it purports to measure, and standardization ensures that the test is administered and scored in a consistent manner. Reliability underpins all of these elements by ensuring that the test results are stable and can serve as a reliable basis for comparison and interpretation.