Question

Which statement is not true regarding the relationship between reliability and validity?

• A. If a measure is perfectly valid, it is also perfectly reliable.
• B. Unreliability implies invalidity.
• C. If a measure is perfectly reliable, it is perfectly valid.
• D. Reliability is a necessary, but not sufficient, condition for validity.

Hint:

Validity \(⇒\) Reliability, but Reliability \(/\!⇒\) Validity. Always check both.

Answer 1

The Correct Option is C

Step 1: Core logic.
- A perfectly valid measure must also be reliable (if it measures the true construct accurately, it cannot fluctuate randomly). ⇒ (a) true.
- If a measure is unreliable, its random error is high; it cannot consistently capture the construct, so it cannot be valid. ⇒ (b) true.
- Reliability is necessary but not sufficient for validity—one can consistently measure the wrong thing. ⇒ (d) true.
Step 2: Identify the false statement.
- (c) is false: high/“perfect” reliability does not guarantee validity (e.g., a perfectly consistent but mis-calibrated thermometer). \[ \boxed{(c)} \]