Showing papers on "False positive paradox published in 1981"

Evaluation of five immunodiagnostic techniques in echinococcosis patients.

Abstract: Double diffusion (DD), indirect haemagglutination (IHA), immunoelectrophoresis (IEP), latex agglutination (LA), and complement fixation (CF) tests were evaluated for sensitivity and specificity in the diagnosis of 141 surgically-proven Turkana echinococcosis patients and 10 controls The overall sensitivities for the tests were: IHA, 867%; LA, 533%; CF, 633%; DD, 550%; IEP, 550% LA and CF tests produced a high number of false positive results; IHA gave a false positive result in 10% of cases; no false positives were obtained with IEP and DD A combination of the latter three tests would therefore offer the best chance of detecting specific anti-Echinococcus antibodies, with an average sensitivity of 627% The possible reasons for the relatively high incidence of false negative values are discussed

Evaluation of methods for detection and quantitation of fetal cells and their effect on RhIgG usage.

Abstract: A 1980 College of American Pathologists Immunohematology Survey included two erythrocyte suspensions, one with and one without fetal cells, designed to evaluate methods for detecting and quantitating fetomaternal hemorrhage in Rh immune globulin candidates Data from a supplementary questionnaire regarding Rh immune globulin administration during 1979 were compared by methods used The most commonly used screening test was the microscopic Du With this test, 122% of nearly 2,000 laboratories obtained a false negative result on an unknown which contained approximately 06% Rh positive erythrocytes On this 100% adult cell suspension two-thirds of laboratories using acid elution technics reported the presence of fetal cells Laboratories using Fetaldex to screen for and quantitate fetomaternal hemorrhage had the highest rate of false positives on this unknown and reported higher rates of multiple vial Rh immune globulin administration when compared to institutions using other acid elution procedures The second unknown in this survey contained approximately 04% fetal cells About one third of laboratories, using each of four acid elution technics, reported values less than one half to more than twice this amount The number of false positive and false negative results and the wide scatter of quantitation amounts reported for these two unknowns suggest that better methods are needed for screening and quantitating fetomaternal hemorrhage

A clinical evaluation of various delta check methods.

Abstract: To evaluate the performance of delta check techniques, we analyzed 707 unselected pairs of continuous-flow test results, using three different delta check methods. If any of the test results (plus the urea nitrogen/creatinine ratio and the anion gap) failed one of the checks, the reason for the failure was sought by examining subsequent test results, retesting specimens, and (or) reviewing te patient's chart. Each delta check failure was accordingly classified as a true or false positive. The percentage of positives we judged to be true positives ranged from 5 to 29%. Each of the three methods had test types with low and high percentages of true positives. We conclude that with the delta check methods one can detect errors otherwise overlooked, but at the cost of investigating many false positives, because, in the population we studied, disease processes or therapy often caused large changes in a series of test results for a patient.

Changes in Delinquency Prevalence: Prediction Problems and Decision Logic in Longitudinal Studies of Delinquency.

Abstract: The relationship between changes in delinquency prevalence over time and prediction error are developed and discussed. Published data from a 21-year British longitudinal study are used to exemplify the formal relationships that are derived. Statistically, as prevalence increases, there will be a relative increase in false negative errors and a decrease in false positive errors; the relationship is independent of prediction accuracy. Substantively, this means that as deliquency prevalence increases, imperfect prediction models will move toward "missing" more actual delinquents (increasing false negatives) and "mistaking" fewer actual nondelinquents (decreasing false positives). Some characterizations of differentially weighting the costs of false negative and false positive errors are presented in terms of intervention and nonintervention policies and decisions.