Kondratovich, Marina (2003). distortion of verification when evaluating diagnostic devices. Proceedings of the 2003 Joint Statistical Meetings, Biopharmaceutical Section, San Francisco, CA. All analyses of diagnostic accuracy variability, which distinguish in advance from explorativen One, would also take into account the purpose of data analysis. In this application, the purpose of the review of the ration agreement is generally not to estimate the accuracy of the assessments by a single advisor. This can be done directly in a validity study comparing evaluations to a final diagnosis that is made from a biopsy. THE CCI ranges from 0 (no agreement) to 1 (perfect agreement). μ j and σ 2 j are the average and variance of the Jth. Note that C b depends in part on “bias” if the interest is to estimate the difference between the means of the two tests, i.e. μ 1 x μ 2. C b is also called the “bia correction factor.” 9 The CCC can therefore be designed as the product of a consistency measure (i.e. the Pearson correlation coefficient) and a distortion measure.
In other words, the CCC quantifies not only how the observations fall on the regression line (by B), but also how close this regression line is to the 45-degree line of perfect concordance (above C b). The FDA recommends the use of the terms of the positive percentage agreement and the negative percentage agreement with the non-reference standard to describe these results. The agreements will be subject to further review in the annexes. Begg, C.G. (1987). Distortion in the evaluation of diagnostic tests. Medical statistics, 6, 411-423. Comparing a new test with a non-reference standard does not provide real performance. If the new test is better than the non-reference standard, the agreement will be bad. Alternatively, the agreement could be bad because the non-reference standard is fairly accurate and the new test is imprecise. There is no statistical solution to determine the scenario of the actual situation. We use the terms “positive percentage agreement” and “negative percentage agreement” with the following precaution.
The agreement of a new test with the non-reference standard differs numerically from the non-reference agreement with the new test (contrary to what the term “agreement” implies). Therefore, when using these measures, the FDA recommends that the agreement clearly state the calculations made. Bland JM, DG Altman. Statistical methods to assess the agreement between two methods of clinical measurement. Lancet 1986;1:307-10. Sensitivity and specificity are basic criteria for a diagnostic test. Together, they describe the extent to which a test can determine whether a given condition is present or non-existent. They provide different and equally important information, and the FDA recommends presenting them together: 95% of bilateral confidence points for a positive percentage agreement and a negative percentage agreement based on the unre referenced standard results observed (variability ignored in the non-reference standard) (78.8%, 96.4%) ( 93,5 %, 98,8 %). A 95% bilateral confidence interval for the total agreement is 92.4%, 97.8% of points.
See Altman et al. (2000) and the latest edition of CLSI EP12-A for a brief discussion on calculating score confidence intervals and, alternatively, how to calculate accurate confidence intervals (Clopper-Pearson). The correct use of terminology to describe performance is important to ensure the safe and efficient use of a diagnostic device. Where possible, this guide uses internationally recognized terminology and definitions, as collected in the Harmonised Terminological Database of the Clinical and Laboratory Standards Institute (CLSI).1 This guide also uses the terms defined in the STARD (STAndards for Reporting of Accuracy) initiative.2 The STARD initiative refers to diagnostic studies.