Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Related Content +++ Quick Reference ++Table Graphic Jump LocationLevels of EvidenceaView Table||Download (.pdf) Levels of Evidencea Level of Evidence Grade Definition 1 A Independent blinded comparison of sign or symptom results with a criterion standard of diagnosis among a large number of consecutive patients suspected of having the target condition 2 B Independent blinded comparison of sign or symptom with a criterion standard of diagnosis among a small number of consecutive patients suspected of having the target condition 3 C Independent blinded comparison of sign or symptom with a criterion standard of diagnosis among nonconsecutive patients suspected of having the target condition 4 C Nonindependent comparison of sign or symptom with a criterion standard of diagnosis among samples of patients who obviously have the target condition plus, perhaps, normal individuals 5 C Nonindependent comparison of sign or symptom with a standard of uncertain validity aModified from Holleman and Simel.13 GET ACCESS TO THIS RESOURCE Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of JAMAevidence 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value JAMAevidence Full Site: One-Year Individual Subscription $495 USD Buy Now View All Subscription Options