The devastating economic effects of the COVID-19 pandemic underscore the need to make public services as effective as possible in future. However, the evidence on how best to achieve this is copious, complex and unstandardized. The confusion is compounded by the existence of a great deal of guidance that does not adhere to quality standards. And because there is currently no accreditation system for guidance producers, it is hard for users to determine which guidance is authoritative.

Evidence for efficacy and cost benefit needs to be generated, synthesized, translated into advice and guidance, and then applied in policymaking and practice (see go.nature.com/37yrrde).

Evidence generation, systematic reviews of evidence, and practice and policy guidelines — such as the updated Appraisal of Guidelines for Research and Evaluation (AGREE) Instrument, AGREE II — need to conform to international standards. Quality marks, which should be displayed prominently, would indicate this conformity. Published guidance, evidence syntheses and trials that do not comply should carry warnings.

Proportionate regulation to ensure standardization is fully justified, given the massive amount spent on public services around the world. What’s at stake here is the public good, which scientific evaluation continues to allow us the opportunity to deliver in education, policing, health care, local government and much else.