title: Why is "hard" evidence "hard" to accept?
authors.forename: David L
authors.initials: DL
authors.lastname: Hahn
mesh_terms: D005540:Forced Expiratory Flow Rates / Q000502:physiology*; D006801:Humans; D011320:Primary Health Care / Q000379:methods* / Q000592:standards; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D011785:Quality Assurance, Health Care; D013147:Spirometry