Which statement best describes reliability and validity and names a common reliability coefficient?

Which statement best describes reliability and validity and names a common reliability coefficient?

• A. Reliability is the extent to which a measure yields consistent results across repeated measurements.
• B. Validity is the degree to which a measure represents the concept of interest in all contexts.
• C. Reliability is consistency of a measure; validity is whether it measures what it's supposed to; Cronbach's alpha is a common reliability coefficient.
• D. Cronbach's alpha measures the validity of a test.

Answer: (C)

Reliability is about consistency: a measure should give similar results across repeated administrations or across its items. Validity asks whether that measure actually captures the concept it’s meant to measure. Cronbach's alpha is a widely used index of reliability that assesses internal consistency among items on a scale, showing whether the items hang together to measure the same construct. This combination of defining reliability and validity clearly, and naming a common reliability coefficient, makes it the best choice. Remember that a measure can be reliable without being valid, and Cronbach's alpha does not assess validity.

Reliability is about consistency: a measure should give similar results across repeated administrations or across its items. Validity asks whether that measure actually captures the concept it’s meant to measure. Cronbach's alpha is a widely used index of reliability that assesses internal consistency among items on a scale, showing whether the items hang together to measure the same construct. This combination of defining reliability and validity clearly, and naming a common reliability coefficient, makes it the best choice. Remember that a measure can be reliable without being valid, and Cronbach's alpha does not assess validity.