title: Problems with the design of observations and their statistical analysis.
authors.forename: H A
authors.initials: HA
authors.lastname: Dudley
mesh_terms: D001652:Bile Ducts / Q000293:injuries; D017081:Cholecystectomy, Laparoscopic / Q000009:adverse effects; D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D006801:Humans; D016017:Odds Ratio; D012107:Research Design; D012189:Retrospective Studies