7.2.6.1  Calculations for a simple kappa statistic

Suppose the K studies are distributed according to numbers a to i as in Table 7.2.a. Then

where

   

is the proportion of studies for which there was agreement, and

is the proportion of studies in which one would expect there to be agreement by chance alone. As an example, from the data in Table 7.2.b,

 

and so

.