title: Classification in two-stage screening.
abstract: Decision theory is applied to the problem of setting thresholds in medical screening when it is organised in two stages. In the first stage that involves a less expensive procedure that can be applied on a mass scale, an individual is classified as a negative or a likely positive. In the second stage, the likely positives are subjected to another test that classifies them as (definite) positives or negatives. The second-stage test is more accurate, but also more expensive and more involved, and so there are incentives to restrict its application. Robustness of the method with respect to the parameters, some of which have to be set by elicitation, is assessed by sensitivity analysis.
authors.affiliation: SNTL and UPF, Barcelona, Spain.
authors.forename: Nicholas T
authors.identifier: http://orcid.org/0000-0003-4129-9726
authors.initials: NT
authors.lastname: Longford
mesh_terms: D015982:Bias; D001943:Breast Neoplasms / Q000175:diagnosis / Q000473:pathology; D016022:Case-Control Studies; D002965:Classification / Q000379:methods*; D003198:Computer Simulation; D003662:Decision Theory; D003955:Diagnostic Tests, Routine / Q000145:classification / Q000592:standards; D005260:Female; D006801:Humans; D015233:Models, Statistical; D012680:Sensitivity and Specificity
keywords: decision theory; loss function; screening; sensitivity analysis; separation