Controlled trials testing two or more treatments simultaneously.
Doll
Richard
R
Clinical Trial Service Unit & Epidemiological Studies Unit, Harkness Building, Radcliffe Infirmary, Oxford OX2 6HE, UK.
D018849:Controlled Clinical Trials as Topic / Q000266:history* / Q000379:methods; D005163:Factor Analysis, Statistical; D005767:Gastrointestinal Diseases / Q000266:history*; D049673:History, 20th Century; D006801:Humans; D016032:Randomized Controlled Trials as Topic / Q000266:history / Q000379:methods; D012107:Research Design