Internal validity causal inference – UGC NET Question

Internal validity refers to the degree to which a study is free from confounding influences and alternative explanations, so that changes in the dependent variable can be ascribed to the independent variable. High internal validity is achieved through control of extraneous variables, random assignment and appropriate design. It is crucial in experimental research where causal claims are being made. Because the stem describes attributing observed changes to the manipulation of the independent variable, internal validity is the correct term.

Option A:
External validity concerns the generalisability of findings to other populations, settings or times, rather than the correctness of causal inference within the study. A study can be internally valid but externally limited, so external validity does not match the stem.

Option B:
Ecological validity focuses on how well research findings reflect real-world behaviours and contexts, often associated with naturalistic settings. While related to generalisability, it is not about directly attributing effects to independent variables in a controlled design. Thus, ecological validity is not the appropriate completion here.

Option C:
Internal validity is enhanced by using control groups, randomisation and standardised procedures to isolate the effect of the independent variable. When these strategies are successful, researchers can more confidently claim that the treatment caused the observed outcomes. This is precisely what the stem is describing.

Option D:
Face validity simply indicates whether a test or study appears, on the surface, to measure what it claims to measure, as judged by laypersons. It does not address deeper issues of causal attribution and control over confounds, so it is not the correct answer.