Observational studies versus randomized trials: squaring off.
Health Policy Research Institute, University of California, Irvine, 100 Theory Ste 110 Irvine, CA 92697-5800, USA.
Sheldon
S
Greenfield
Sherrie H
SH
Kaplan
D015906:Angioplasty, Balloon, Coronary; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male