Specificity, sensitivity

An inventory of existing test methods, together with an appreciation of the scientific validity, sensitivity, specificity and reproducibility of these methods. 

Monoclonal antibodies are very sensitive, specific reagents and have applications in many areas of the biological sciences. They revolutionized immunology within a few years of their discovery. 

Once the determinative or confirmatory method has been developed to take full advantage of the chemical properties of the analyte molecule, a study is necessary to prove that the method is valid. Criteria for method validation are outlined in guidelines from the US FDA, US EPA, and EU. A summary of the differences in regulatory requirements for method validation is provided in Table 3. The parameters addressed by all of the regulatory guidelines include accuracy, precision, sensitivity, specificity, and practicability. 

NPD (FTD) Relatively high sensitivity Specific response Smaller dynamic range than FID Susceptible to operating conditions [31]... 

A new tumor marker is evaluated using the same criteria used for many diagnostic tests (i.e., sensitivity, specificity, and accuracy). The diagnostic sensitivity and specificity are best represented by a receiver operating characteristic (ROC) curve. The ROC curve is constructed with the true-positive rate versus false-positive rate at various decision levels. As a test improves in its diagnostic performance, it shifts upward and to the left as the true-positive rate increases and the false-positive rate decreases. 

It is recommended that the protocol itself contain language that allows for minor modifications of an analytical method or procedure without necessitating an amendment (or a deviation) for example, "Minor modifications in instrumental parameters and/or adjustments in technique may be made in the method during specimen analysis to enhance overall efficiency or the sensitivity, specificity, or selectivity of analyte response."... 

Events involving deliberate or accidental distribution of bacterial pathogens into our everyday environment have clearly defined the need for a sensitive, specific, and rapid method of bacterial detection. Bioterrorism was first introduced in the United States in 1984 with the Salmonella typhimurium attack in The Dalles, Oregon, by a cult group attempting to affect a local election.1 As a result of this act 751 people contracted salmonellosis, which totally overwhelmed the hospitals and medical clinics with patients. Later our society became keenly aware of the potential of bioterrorism during the last four months of 2001 when Bacillus anthracis (anthrax) spores were sent through the US mail in an envelope to several locations. These events had... 

The principal advantages of RIA are its sensitivity, specificity and simplicity of operation. There are three main disadvantages. Firstly, the lengthy development periods for new methods often result from the difficulties of producing the specific binding agent. Secondly, cross-reactions with other molecules similar to the analyte can sometimes interfere. Thirdly, poor precision can result unless careful control of experimental conditions is employed to ensure reproducible binding reactions. Relative precisions of 1-3% are typical. 

Chemical vapor sensors play an ever-increasing role in the environmental monitoring, homeland security, defense, and health care. The desirable characteristics of a chemical vapor sensor include ultrahigh sensitivity, specific and rapid response to certain vapor molecules, as well as the ability for on-the-spot chemical analysis, which usually requires the sensor to be small, portable, reusable, stable, robust, and cost effective. Toward this end, various sensing techniques have been studied... 

The authors also evaluated the performance of various DES-T and DES cutoffs for detecting taxon members defined by Bayesian probabilities. Waller and Ross found that DES-T cutoffs work much better than the cutoffs on the DES because they have higher sensitivity, specificity, and positive and negative predictive values. One could say that the authors stacked the deck in favor of the DES-T, as the Bayesian probabilities and DES-T scores are based on the same data. However, this redundancy is unavoidable, since there is no other method of assessing taxon membership. It is important to evaluate the qualities of DES-T cutoffs for studies that will use the DES-T, rather than the Bayesian scoring scheme. 

Data to establish the clinical validity of genetic tests (clinical sensitivity, specificity, and predictive value) must be collected under investigative protocols" (Holtzman and Watson, 1998, p. 28). 

The model immunoassay is the enzyme-linked immunosorbent assay (ELISA) in which a non-specific capture antibody is bound to a surface, such as a multi-well plate or small tube [13]. In the basic form of ELISA, a second antibody tagged with an enzyme interacts specifically with the analyte. The enzyme assay produces a colored product that is read with a spectrophotometer. There are many variations on the basic immunoassay format that serve to increase sensitivity, specificity, linear range, and speed. Many commercial instruments have been developed to take advantage of various technologies for reporter molecules. The immunoassay may be coupled to an electronic sensor and transducer, such as a surface acoustical wave (SAW) sensor. Electrochemiluminescence (ECL) is a method in which the detector antibody is tagged with a ruthenium-containing chelate [13-15]. When the tag is... 

Most researchers, even those who can deal with sensitivity, specificity, and predictive values, throw in the towel when it comes to Bayes theorem. This is odd, because a close look at the equation reveals that Bayes theorem is merely the formula for the positive predictive value (Box and Tiao, 1973). 

Barbiturates represent a class of sedative and hypnotic drugs employed extensively in medicine. RIA provides a rapid, sensitive specific and reliable means for their determination in plasma levels upto 5 ng without indulging in any type of extraction, filtration or evaporation as required for other conventional analytical methods. ... 

Stripping (General), the techniques and methodology of analyte preconcentration used in voltammetry to improve the sensitivity (specific), the electrochemical re-removal of analyte accumulated at an electrode. 

The accuracy, sensitivity, specificity, and reproducibility of test methods employed by the firm shall be established and documented. ... 

Reliable quality control in the field of pharmaceutical analysis is based on the use of valid analytical methods. For this reason, any analytical procedures proposed for a particular active pharmaceutical ingredient and its corresponding dosage forms shonld be validated to demonstrate that they are scientifically sonnd nnder the experimental conditions intended to be used. Since dissolntion data reflect drng prod-net stability and quality, the HPLC method used in snch tests shonld be validated in terms of accuracy, precision, sensitivity, specificity, rngged-ness, and robustness as per ICH guidelines. 

The aforementioned procedures (techniques) have significant potential and as assay problems are worked out could provide rapid, sensitive, specific and precise methods for the analysis of low levels of antibiotics in food and feed products. 

Close cooperation for a year or more before the first administration to humans is likely to lead to a smooth transfer of the compound and the rapid movement of a compoimd out of preclinical into man. This lead time can be used to devise the ED plan, design the first studies and, when appropriate, to select and develop methodologies that will contribute to the drug s evaluation in man. This may include validation of pharmacod)mamic measures to be used in the clinical pharmacology unit, assessment of various imaging techniques, development of bioanalytical methods. Not infrequently, the assays that were perfectly adequate to support preclinical work are insufficiently sensitive, specific or accurate to quantify the comparatively low concentrations of parent... 

No data were located concerning methods to measure biological markers of hexachlorobutadiene effects. Research into biomarkers of effect would be most useful if performed in conjunction with development of sensitive, specific, and reliable methods for measuring the biomarker(s) of effect. 

Models Bayesian score Sensitivity Specificity % of unclassified... 

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