What characteristic ensures a test measures what it claims to measure?

The characteristic that ensures a test measures what it claims to measure is validity. Validity indicates the extent to which a test accurately reflects the concept or construct it is designed to assess. In other words, a valid test provides an accurate representation of the skill, ability, or knowledge it intends to measure, ensuring that the outcomes are meaningful and applicable.

For instance, if a test is designed to evaluate a student's understanding of mathematical concepts, it should accurately assess that knowledge rather than assessing unrelated skills like reading comprehension. Validity can be evidenced through various means, such as content validity (how well the test content represents the domain), construct validity (the degree to which the test measures the theoretical construct it is intended to measure), and criterion-related validity (how well one measure predicts outcomes based on another measure).

The other characteristics mentioned play important roles in assessment, but they serve different purposes. Comprehensiveness refers to how well the test covers all relevant content; reliability refers to the consistency of the test results over time or across different test conditions; and objectivity concerns the reduction of bias in scoring. While these qualities are important for a well-rounded test, they do not define the fundamental nature of a test's ability to measure what it purports to measure,