Which term describes the extent to which an instrument measures what it is intended to measure?

The term that describes the extent to which an instrument measures what it is intended to measure is validity. Validity is a crucial concept in psychology and research because it determines how well a test or assessment accurately reflects the concept or construct it is designed to assess. For instance, if a psychological test claims to measure intelligence, high validity means that the test indeed accurately measures intelligence rather than some other factor.

On the other hand, reliability refers to the consistency of a measurement over time or across different situations, accuracy relates to the closeness of a measurement to the true value, and consistency relates to the reproducibility of results. While all of these terms are important in measuring research instruments, validity specifically addresses the degree to which the intended construct is captured, making it the correct choice in this context.