Reliability and validity in measurement refer to which of the following?

• A. Reliability is consistency; validity is whether the measure assesses the intended construct
• B. Reliability and validity are the same concepts
• C. Reliability concerns bias; validity concerns sampling
• D. Validity is the same as generalizability

Answer: (A)

Reliability and validity are two essential properties of measurement. Reliability is about consistency—if you measure the same trait repeatedly or with different items intended to gauge the same construct, you should get similar results. Validity is about accuracy—does the instrument actually measure the intended construct and not something else?

The best answer states that reliability means consistency, and validity concerns whether the measure assesses the intended construct. You can have a tool that is reliable but not valid if it produces consistent results that don’t reflect what you mean to measure. Conversely, a tool could be valid in what it intends to measure but still be imperfectly reliable in some contexts. The other ideas—that reliability and validity are the same, or that reliability is about bias while validity is about sampling, or that validity equals generalizability—don’t capture the distinct meanings and roles these concepts play in measurement.