What is essential for a test to possess aside from reliability to be considered useful?

For a test to be considered useful, validity is essential in addition to reliability. Reliability refers to the consistency of the test results, while validity assesses whether the test measures what it is intended to measure. A test that is reliable but not valid does not provide meaningful or actionable results, making it ineffective for evaluation or decision-making processes.

For instance, a test could consistently produce the same scores (high reliability) but fail to accurately assess an individual's skills or knowledge in a certain area (low validity). Therefore, without validity, even a highly reliable test may lead to misguided conclusions or interventions.

On the other hand, high cost of administration, long testing duration, and diverse test items do not inherently contribute to the fundamental usefulness of a test. A useful test should ideally be practical and efficient while delivering valid and reliable results. Hence, establishing a strong foundation of validity is critical to ensure that the test serves its intended purpose effectively.