Investigators apply the term validity to multiple aspects of drug developments: animal models, interpretations of outcome data, statistical analyses, generalizations beyond the subject sample, and so forth. Validity implies that the study can be replicated and the conclusions applied successfully in different settings and over time (39). Given the wide range of often silent errors and bias threats to psychiatric drug development and CTs, claims of validity are best regarded with suspicion. A process or result can be labeled as valid without specific evidence that errors or biases do not account for outcomes (36). Undetected error or bias effects may silently nullify an apparently valid study. CTs currently regarded as valid may in fact be invalid as a result of hidden or subtle methodological shortcomings (25).
