title: The use of the 'reverse Cornfield inequality' to assess the sensitivity of a non-significant association to an omitted variable.
abstract: Unlike randomized experimental studies, investigators do not have control over the treatment assignment in observational studies. Hence, the treated and control (non-treated) groups may have widely different distributions of unobserved covariates. Thus, if observational data are analysed as if they had arisen from a controlled study, the analyses are subject to potential bias. Sensitivity analysis is a technique for assessing whether the inference drawn from a study could be altered by a moderate 'imbalance', between the distribution of the covariates in different groups. In this paper, we examine the sensitivity analysis of the test of proportions in 2 x 2 tables from a new perspective: 'could a non-significant result have occurred because the treated group has a higher prevalence of an unobserved risk factor?'. The study was motivated by an analysis of the studies concerning with the possible effect of spermicide use on birth defects that were cited in a legal decision.
authors.affiliation: Information Management Services, Inc., 12501 Prosperity Dr. Suite 200, Silver Spring, MD 20904, USA. yu@ims.nci.nih.gov
authors.forename: Binbing
authors.initials: B
authors.lastname: Yu
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Gastwirth
mesh_terms: D000704:Analysis of Variance; D016022:Case-Control Studies; D006801:Humans; D017880:Limb Deformities, Congenital / Q000209:etiology; D008175:Lung Neoplasms / Q000209:etiology; D015233:Models, Statistical; D015588:Observer Variation; D016017:Odds Ratio; D018570:Risk Assessment / Q000706:statistics & numerical data*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012907:Smoking / Q000009:adverse effects; D013089:Spermatocidal Agents / Q000009:adverse effects; D014149:Tranquilizing Agents / Q000009:adverse effects
chemical_list: D013089:Spermatocidal Agents; D014149:Tranquilizing Agents