Exercise: observer agreement about sex, answer 2


What does kappa mean and what can we conclude?

Suggested answer

Kappa is a measure of the agreement between two observers. It is the amount by which the observed agreement exceeds the agreement we would expect if the two observations were unrelated, divided by the maximum possible value of this. The maximum possible is one minus the expected proportion agreeing.

kappa = (0.9891 – 0.5452)/(1 – 0.5452) = 0.976

As the maximum possible kappa is 1.00 and we have observed 0.976, we have very good agreement. In this case, it would be a shock if we didnít, of course.

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