Positive Agreement Sensitivity

Due to COVID-19, there is currently a great deal of interest in the sensitivity and specificity of a diagnostic test. These terms refer to the accuracy of a test for the diagnosis of a disease or condition. To calculate these statistics, the actual condition of the subject must be known, whether the subject has disease or condition. diagnoses based on the chain reaction of reverse transcription transcription (RT-PCR) or non-thermocycling probes report a detection limit-based test sensitivity (LoD), defined as the lowest amount of target that the test can detect, at least 95% of the time; a lower LD indicates a more sensitive test. Specificity is assessed on the basis of the genomic nature of the occurrence or not of a multiplicity of other pathogens. Tests with binary results are generally evaluated based on the sensitivity and specificity that are inherent in the test. The objective definition of sensitivity and specificity requires a standard of reference — a test generally recognized as the best method available to determine the existence or absence of a condition. If no benchmark is available, sensitivity and specificity are defined as a positive percentage agreement (AAE) and a negative percentage agreement (NPA) with another developer`s choice test. To address this problem, NPV and APP should only be used if the ratio of the number of patients in the disease group to the number of patients in the healthy control group used to determine APA and APA corresponds to the prevalence of disease in the study population or, if two disease groups are compared , if the ratio between the number of patients in group 1 and the number of patients in group 1 and the number of patients in group 1 Patients in group 2 correspond to the ratio between the prevalence of the two diseases studied. Otherwise, the positive and negative probabilities are more accurate than the APP and the APA, as the probabilities do not depend on prevalence. Nor do these statistics support the conclusion that one test is better than another. Recently, a British national newspaper published an article on a PCR test developed by Public Health of England and the fact that with a new commercial test in 35 samples out of 1144 (3%) disagreed.

Of course, for many journalists, this was proof that the PHE test was imprecise. There is no way to know which test is correct and which is wrong in any of these 35 discrepancies.

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