title: Absence of evidence is not evidence of absence.
authors.affiliation: Medical Statistics Laboratory, Imperial Cancer Research Fund, London.
authors.forename: D G
authors.initials: DG
authors.lastname: Altman
authors.forename: J M
authors.initials: JM
authors.lastname: Bland
mesh_terms: D018849:Controlled Clinical Trials as Topic; D003627:Data Interpretation, Statistical; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D018401:Sample Size; D013223:Statistics as Topic