Figure 2.

Kappa (κ) values in relation to percent agreement. Horizontal bars show the percent agreement (PA, red bars + orange bars), relative to the maximal possible percent agreement (100%, ends of white bars). The lengths of red bars show the percent agreement estimated to be attributable to chance, PC, used in estimating the degree of IRA, κ. The total percentage of possible agreement beyond each red bar, 100-PC (orange bar + white bar) is considered the potential degree of agreement achievable “beyond chance,” whereas the beyond-chance agreement actually achieved is PA–PC (the length of the orange bars). Mathematically, the chance-corrected IRA, κ, is the percentage of this possible beyond-chance agreement that is actually achieved, that is, $\kappa =\frac{\text{PA}-\text{PC}}{100-\text{PC}}$. Graphically, this mathematical definition of κ is represented as the fraction of the distance between 100% and the end of the red bar that is taken up by the orange bar. Abbreviations are the same as in Figure 1.

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