Distinguish reliability from validity.

• A. Reliability is consistency of measurement; validity is how well a measure assesses what it intends to assess.
• B. Reliability is about measuring what you intend; validity is about consistency.
• C. Reliability and validity are interchangeable terms in psychology research.
• D. Reliability is about causality; validity is about reliability across time.

Answer: (A)

Reliability is about consistency—whether a measurement yields the same results across repeated trials or different raters. Validity is about accuracy in what the measure is supposed to capture—whether it actually assesses the intended construct. A tool can be consistently off (reliable but invalid) if it gives the same wrong answer each time, like a scale that always reads 5 pounds too heavy. On the other hand, a measure can be valid in what it aims to assess but still have some inconsistency (not perfectly reliable), though reliability is generally needed for strong validity. So the best description is that reliability = consistency of measurement, validity = how well the measure assesses what it intends to assess.