title: Pooling of studies in meta-analysis of observational research leads to precise but spurious results.
authors.forename: C W
authors.initials: CW
authors.lastname: Bollen
authors.forename: M O
authors.initials: MO
authors.lastname: Hoekstra
authors.forename: H G M
authors.initials: HG
authors.lastname: Arets
mesh_terms: D002648:Child; D016724:Empyema, Pleural / Q000628:therapy*; D006801:Humans; D015201:Meta-Analysis as Topic; D012107:Research Design