Threats to internal validity – UGC NET Question

Statement E is the only wrong statement because random assignment actually strengthens internal validity by equalising groups on extraneous variables. History, maturation, testing and instrumentation are all recognised threats that can introduce alternative explanations for observed changes if not controlled. Thus, A, B, C and D accurately name and describe typical threats, while E reverses the protective role of random assignment.

Option A:
Option A is incorrect because it groups A with E as wrong, even though A correctly defines history as external events occurring during the study period. Misclassifying A undermines the standard taxonomy of threats.

Option B:
Option B is also wrong because it treats B along with E as incorrect, even though B adequately describes maturation as internal changes over time. Including B among wrong statements disrupts the understanding of developmental influences on participants.

Option C:
Option C is correct because it isolates E, the statement that conflicts with experimental logic, and implicitly affirms the accuracy of A, B, C and D. It recognises that random assignment is a remedy, not a threat.

Option D:
Option D is incorrect because it pairs C with E, even though C correctly identifies testing effects. By labelling C as wrong, this option denies a well-acknowledged validity threat.