CLSI EP12: User Protocol for Evaluation of Qualitative Test Performance Protocol describes the terms of the Positive Percentage Agreement (AEA) and the Negative Performance Agreement (NPA). If you have two binary diagnostic tests to compare, you can use an agreement study to calculate these statistics. 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. We simply do not know the actual state of the subject in unit studies. Only further investigation into these discrepancies would identify the reasons for these discrepancies. In the FDA`s latest guidelines for laboratories and manufacturers, "FDA Policy for Diagnostic Tests for Coronavirus Disease-2019 during Public Health Emergency," the FDA explains that users should use a clinical trial to establish performance characteristics (sensitivity/AAE, specificity/NPA). While the concepts of sensitivity/specificity are widely known and used, the terms AAE/APA are not known. In the next blog post, we`ll show you how to use Analysis-it to perform the contract test with a treated example.
To avoid confusion, we recommend that you always use the terms positive agreement (AAE) and negative agreement (NPA) when describing the agreement of these tests. Although the positive and negative matching formulas are identical to those for sensitivity/specificity, it is important to distinguish them because the interpretation is different. Multiply z.B 0.5 per 100 to get a total agreement of 50 percent. If you want to calculate z.B. the match percentage between the numbers five and three, take five minus three to get the value of two for the meter. When calculating the percentage agreement, you must determine the percentage of the difference between two digits. This value can be useful if you want to show the difference between two percentage numbers. Scientists can use the two-digit percentage agreement to show the percentage of the relationship between the different results.