Observational study

Registries and real-world data studies are often observational. They can support postmarket evidence and sometimes premarket decisions, but without randomization they need careful control of bias and confounding.

Study that draws inferences about the possible effect of an intervention on subjects, but the investigator has not assigned subjects into intervention groups.

FDA guidance: Design Considerations for Pivotal Clinical Investigations for Medical Devices (November 2013), Section 11, Glossary