Exercise: observer agreement about eye colour, answer 2

Question

The expected agreement is much lower than for sex, where it was 54.52%. Why is this?

Suggested answer

There are many more cells in the eye colour table, 7×7 = 49, compared to 4 in the sex table, and only 7 of them, 7/49 = 14%, are where there would be agreement, compared to 2/4 = 50% in the sex table. Hence there is less scope for expected or chance agreement in the eye table than in the sex table.

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