False positives INDEX

The ProstAsure index, developed by Zhang, Stamey, and Chan, was designed to increase the sensitivity and specificity of cancer detection, while maintaining a reasonable false positive detection rate. The index is derived firom several values, including age, total PSA, creatine kinase isoenzymes, and prostatic acid phosphatase, which are input... 

Compared to viruses, many problems are still associated with the routine indexing of plant materials for pathogenic bacteria ELISA is less sensitive than Immunofluorescence microscopy and both methods Involve a risk of false positive reactions due to cross-reacting saprophytic micro-organisms, particularly when antisera are not properly tested ... 

Two other PMs are the reliability index (A q ) and the Matthews coeffi-cient. The reliability index is a measure of the number of false positives. It is defined as follows ... 

A test that can be used to assess liver function when other liver function tests are normal. It is a test of the ability of the liver to conjugate and excrete the dye bromsulphthalein (BSP). It consists of an intravenous injection of the dye followed by the collection of blood specimens up to 45 minutes after the injection. Bromsulphthalein is then measured in the serum samples by adding alkali which renders the dye purple. In normal subjects less than 5% of the dose should remain in the circulation after 45 minutes. Increased retention of BSP is a sensitive index of hepatic dysfunction although false positives may occur if there is impaired circulation in the liver. 

Index Area Overlap False Positive Rate False N ative Rate ... 

A more difficult criterion to meet with flow markers is that the polymer samples not contain interferents that coelute with or very near the flow marker and either affect its retention time or the ability of the analyst to reproducibly identify the retention time of the peak. Water is a ubiquitous problem in nonaqueous GPC and, when using a refractive index detector, it can cause a variable magnitude, negative area peak that may coelute with certain choices of totally permeated flow markers. This variable area negative peak may alter the apparent position of the flow marker when the flow rate has actually been invariant, thereby causing the user to falsely adjust data to compensate for the flow error. Similar problems can occur with the elution of positive peaks that are not exactly identical in elution to the totally permeated flow marker. Species that often contribute to these problems are residual monomer, reactants, surfactants, by-products, or buffers from the synthesis of the polymer. 

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