title: Observational studies of treatment effectiveness: useful, useless or somewhere in between?
authors: Ruth Ann
authors: RA
authors: Marrie
mesh_terms: D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000627:therapeutic use*; D008297:Male; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000188:drug therapy*
chemical_list: D007155:Immunologic Factors