Kappa`s statistic, which is a number between -1 and 1. The maximum value is full consent; Zero or less means a deal of luck. We find that it shows a greater resemblance between A and B in the second case, compared to the first. Indeed, if the percentage of agreement is the same, the percentage of agreement that would occur “by chance” is much higher in the first case (0.54 vs. 0.46). The statistic of – can take values from 1 to 1 and is interpreted arbitrarily as follows: 0 – concordance that corresponds to chance; 0.10-0.20 – light approval; 0.21-0.40 – fair agreement; 0.41-0.60 – moderate support; 0.61-0.80 – substantial agreement; 0.81-0.99 – near-perfect chord; and 1.00 – perfect chord. The negative results suggest that the observed agreement is worse than one might expect. An alternative interpretation is that Kappa values below 0.60 indicate a considerable degree of disagreement. Cohens Kappa () calculates the agreement between observers taking into account the agreement expected by chance as follows: The field in which you work determines the acceptable level of consent. If it is a sporting competition, you can accept a 60% agreement to nominate a winner. However, if you look at the data from oncologists who choose to take a treatment, you need a much higher agreement – more than 90%. In general, more than 75% are considered acceptable in most areas. Cohen`s Kappa formula for two advisors is: where: Po – the relative correspondence observed among the advisors.
Pe – the hypothetical probability of a coincidence agreement To establish the value of Kappa, we must first know the probability of an agreement (this explains why I highlighted the agreement diagonally). This formula is derived by adding up the number of tests in which the raters accept, and then dividing them by the total number of tests. In the example of Figure 4, this would mean (A-D) / (A -B-C-D). A -> The total number of proceedings that both councillors said were correct. The councillors agree. Cohens Kappa measures the agreement between two advisors who classify each of the N elements into exclusion categories C. The definition of “Textstyle” is as follows: after all, the formula for Cohens Kappa is the probability of an agreement that removes the probability of a fortuitous agreement, divided by 1 minus the probability of a fortuitous agreement. Bland and Altman expanded this idea by graphically showing the difference in each point, the average difference and the limits of vertical match with the average of the two horizontal ratings.