title: APPROACHES TO EXPERIMENTAL DESIGN IN CLINICAL RESEARCH.
mesh_terms: D035843:Biomedical Research; D004358:Drug Therapy; D006801:Humans; D006919:Hydroxyzine; D008614:Meperidine; D010919:Placebos; D011229:Preanesthetic Medication; D012106:Research; D012107:Research Design
chemical_list: D010919:Placebos; D006919:Hydroxyzine; D008614:Meperidine
keywords: CLINICAL RESEARCH; DRUG THERAPY; HYDROXYZINE; MEPERIDINE; PLACEBOS; PREANESTHETIC MEDICATION; RESEARCH