Placebo effect

Device studies can show large placebo effects, especially with procedures and subjective endpoints. Without a control group, such effects can be mistaken for device effectiveness.

A physical or psychological change, occurring after an ineffective device is used, that is not the result of any special property of the device. The change may be beneficial, reflecting the expectations of the participant and, often, the expectations of the person using the device.

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