Cohens Kappa is a measure of compliance calculated in the same way as the example above. The difference between Cohen`s Kappa and what we just did is that Cohens Kappa also looks at situations where spleeners use certain categories more than others. This has an impact on the calculation of the probability that they will agree by chance. For more information, see Cohens Kappa. Missing data is omitted by list. The use of the advanced agreement as a percentage (tolerance!-0) is only possible for numerical values. If tolerance is z.B. 1, spleens that differ by one degree of scale are considered consenting. So on a scale from zero (chance) to a (perfect), your approval in this example was about 0.75 – not bad! In the case of realistic datasets, calculating the percentage of agreement would be both laborious and error-prone. In these cases, it would be best to get R to calculate it for you so that we practice your current registration. We can do this in a few steps: although we have been definitively rejected as an appropriate measure of the IRR (Cohen, 1960; Krippendorff, 1980), many researchers continue to report on the percentage agreed by coders in their ratings as a coder agreement index. For classified data, this can be expressed as the number of agreements in observations divided by the total number of observations. In the case of ordinal data, intervals or reports, where close but not perfect agreement may be acceptable, the percentages of agreement are sometimes expressed as a percentage of evaluations that coincide over a certain interval.
Perhaps the biggest criticism of the percentages of the agreement is that they are not correct for agreements that would be expected by chance and therefore overestimate the level of the agreement. For example, if coders rated 50% of subjects as «depressive» at random and 50% as «non-depressive,» regardless of the actual characteristics of the subject, the expected percentage of the agreement would be 50%, while all overlapping evaluations would be random. If coders randomly rated 10% of subjects as depression and 90% non-depressive, the expected percentage of the agreement would be 82%, although this apparently high level of correspondence is always due to chance alone. Kappa`s statistics measure the degree of agreement observed between coders for a number of nominal ratings and corrections for an agreement that would be expected by chance, and offer a standardized index of IRR that can be generalized between studies. The observed degree of match is determined by cross-tables for two coders, and the randomly expected agreement is determined by the frequencies of each coder`s ratings.