Reliability and validity of instruments – UGC NET Question

Statements A, B and E capture the essential ideas of reliability and validity in measurement. Statement A is correct because reliability refers to the consistency or stability of scores obtained with an instrument. Statement B is true in stating that validity concerns whether the instrument measures what it is supposed to measure. Statement E is also correct since the test–retest approach is a common method of estimating reliability, whereas statement C is false because validity generally presupposes a certain level of reliability and statement D is false because high reliability alone does not guarantee validity.

Option A:
Option A includes two correct statements but omits statement E. Since test–retest is a recognised method for estimating reliability, leaving out E means that the combination does not include all the true statements in the list. Consequently, Option A cannot be considered the correct answer.

Option B:
Option B combines B and E but ignores statement A. Although B and E are true, excluding A leaves out the basic notion that reliability is about the consistency and stability of an instrument’s scores. Because the option fails to include all the correct statements, it is incomplete and hence incorrect.

Option C:
Option C adds statement C to otherwise correct statements A, B and E. However, C is misleading because in psychometric theory an instrument that is not reliable cannot meaningfully be valid; reliability is typically a prerequisite for validity. Including a false or misleading statement makes the whole combination unacceptable.

Option D:
Option D lists A, B and E and excludes both C and D, which are false or misleading statements. It accurately reflects that reliability refers to consistency, validity to what is actually measured, and that test–retest is one way of assessing reliability. Since it contains all and only the true statements, this option is the correct answer.