Some researchers have expressed concern about the tendency of κ to take as data the frequencies of the observed categories, which may make them unreliable for measuring concordance in situations such as the diagnosis of rare diseases. In these situations, κ tends to underestimate the concordance on the rare category.  This is why κ is considered too conservative a degree of convergence.  Others[citation required] dispute the assertion that kappa “takes into account” random agreement. To do this effectively, there would need to be an explicit model of the impact of chance on evaluators` decisions. The so-called random adjustment of kappa statistics assumes that, if it is not entirely certain, evaluators simply advise – a very unrealistic scenario. To calculate pe (probability of a random match), we find that: Kappa accepts its maximum theoretical value of 1 only if the two observers distribute equal codes, that is, if the corresponding amounts of rows and columns are identical. Everything is less than a perfect match. Nevertheless, the maximum value that kappa could reach in the case of unequal distributions makes it possible to interpret the actually conserved value of kappa. The equation for the maximum κ is:  Here, the coverage of quantity and assignment conflicts is instructive, while Kappa conceals the information. In addition, Kappa introduces some challenges in calculation and interpretation, as Kappa is a ratio. It is possible that the kappa ratio returns an indefinite value due to zero in the denominator.
Moreover, a report does not betray either its counter or its denominator. It is more informative for researchers to point out disagreements in two components, quantity and allocation. These two components describe the relationship between the categories more clearly than a single summary statistic. If forecast accuracy is the goal, researchers can more easily think about how to improve forecasting by using two components of quantity and allocation instead of a Kappa report.  Purpose. Comparison of full-threshold (FT) and SITA algorithms for standard automated permetry (SAP) with perimetry doubling frequency (FDT) technology in glaucoma, to help clinicians compare outcomes in patients who had two or more of these tests during follow-up. A case that is sometimes considered a problem with Cohen`s kappa occurs if one compares the Kappa calculated for two pairs of evaluators, with both evaluators in each pair with the same percentage of concordance, but one pair gives a similar number of evaluations in each class, while the other pair gives a very different number of grades in each class.  (In the following cases, note B has 70 votes in favour and 30 against in the first case, but these figures are reversed in the second case.) For example, in the following two cases, there is an equality of correspondence between A and B (60 out of 100 in both cases) with respect to the correspondence in each class, so we would expect the relative values of Kappa cohens to reflect this. Cohen`s Kappa calculation for each: the deductible, however, determines the minimum threshold of financial liability of insurance companies.