Do reliability and validity always exist together?

Do reliability and validity always exist together?

• A. Yes
• B. No
• C. Sometimes
• D. In all cases

Answer: (B)

Reliability and validity are about different qualities of a measurement. Reliability means scores are consistent across repeated measurements or raters. Validity means the scores actually reflect the thing you intend to measure and relate to other evidence in expected ways. These two don't always go together. A test can be very reliable—giving nearly identical results across trials—yet be invalid if it isn't measuring the intended construct. For example, a questionnaire that consistently yields the same scores but taps general fatigue rather than the specific trait you want to assess would be reliable but not valid. Conversely, you might see some validity evidence even if there’s some measurement error, but high reliability is not, by itself, a guarantee of validity. So reliability and validity do not always exist together.

Reliability and validity are about different qualities of a measurement. Reliability means scores are consistent across repeated measurements or raters. Validity means the scores actually reflect the thing you intend to measure and relate to other evidence in expected ways.

These two don't always go together. A test can be very reliable—giving nearly identical results across trials—yet be invalid if it isn't measuring the intended construct. For example, a questionnaire that consistently yields the same scores but taps general fatigue rather than the specific trait you want to assess would be reliable but not valid. Conversely, you might see some validity evidence even if there’s some measurement error, but high reliability is not, by itself, a guarantee of validity. So reliability and validity do not always exist together.