Stochastic curtailing and conditional power in matched case-control studies.
New methodology for early stopping of observational epidemiologic studies is developed. To indicate the likelihood of a positive result at the end of a study, the conditional power (CP) is calculated using an approach similar to that of Halperin et al. Given the current result, the conditional probability of a positive result for the entire study is determined. An expression relating the new approach to an approach given by Lan and Wittes is derived. As an example, the CP is calculated based on information from the first third of a matched case-control study embedded in an epidemiological study.
Biostatistics Research Branch, National Heart, Lung and Blood Institute, Bethesda, MD 20892.
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S
Hunsberger
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Sorlie
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NL
Geller
D000914:Antibodies, Viral / Q000097:blood; D001161:Arteriosclerosis / Q000276:immunology / Q000401:mortality; D015982:Bias; D016022:Case-Control Studies; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D003324:Coronary Artery Disease / Q000276:immunology / Q000401:mortality; D003587:Cytomegalovirus / Q000276:immunology; D003627:Data Interpretation, Statistical; D005500:Follow-Up Studies; D018259:Herpesvirus 1, Human / Q000276:immunology; D018258:Herpesvirus 2, Human / Q000276:immunology; D006801:Humans; D011446:Prospective Studies; D012307:Risk Factors; D013269:Stochastic Processes; D016019:Survival Analysis
D000914:Antibodies, Viral