title: Selection bias in observational studies: out of control?
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Beck
mesh_terms: D015331:Cohort Studies; D015897:Comorbidity; D003627:Data Interpretation, Statistical; D006801:Humans; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000453:epidemiology*; D011897:Random Allocation; D012042:Registries / Q000592:standards; D015983:Selection Bias; D011795:Surveys and Questionnaires / Q000592:standards