Which concept relates to testing to determine if it measures all aspects of the given subject?

The concept that pertains to assessing whether a test measures all facets of a given subject is known as content validity. Content validity examines whether the items included in a test appropriately represent the domain or construct being measured. This is essential in ensuring that the test is comprehensive and relevant to the specific subject matter. For instance, if a test is designed to assess mathematical skills, content validity would require that the questions cover all relevant areas of mathematics that are part of the curriculum, rather than focusing narrowly on only one aspect.

Content validity is typically established through expert judgment, where subject matter experts review the test items to determine whether they adequately represent the construct in question. This evaluation helps ensure that the test captures the breadth of knowledge or skills that it is intended to assess, making it a crucial consideration in the development of reliable and valid assessments.