Translating scientific evidence into effective policies for health and technology requires care.
Selecting high-quality evidence is only part of the challenge. “Good evidence” must be paired with the “good governance of evidence”. Key Insights Professional science organisations that have examined social media and adolescent mental health have reached different conclusions and policy recommendations despite examining similar research. Given their substantial influence on policy and public understanding , it is important to investigate their evidence synthesis practices. Our analysis of three high-profile reports on social media and adolescent mental health finds that they cited broadly similar types of research, yet showed little overlap (<1%) in their sources. We also found considerable variation in how the reports synthesize, communicate, and simplify evidence, including differences in citation accuracy, contextual detail, limitation acknowledgement, and conclusion strength. The stakes of getting these syntheses right are substantial. Poor synthesis quality risks deve...