Which type of validity refers to the generalizability of trial results?

• A. Internal validity
• B. External validity
• C. Content validity
• D. Construct validity

Answer: (B)

External validity is the type of validity that refers to the generalizability of trial results. It assesses the extent to which the findings of a study can be applied to or have relevance for settings, people, and times beyond the specific conditions of the study. External validity is crucial for determining how the results can be interpreted in a broader context and for informing clinical practice or policy decisions based on a study's outcomes.

In practice, a study with high external validity implies that its results can be applied to wider populations or different circumstances, making the findings more useful and applicable in real-world scenarios. This contrasts with internal validity, which focuses on the accuracy of the relationships within the study itself and whether the study design and execution minimize biases or errors.

Content validity relates to whether a test or instrument fully represents the concept being measured, while construct validity evaluates whether a test truly measures the theoretical construct it's intended to measure. These forms of validity are more concerned with the specifics of the measurement and less about the broader applicability of the results, underscoring the unique role of external validity in research.