Two raters independently classify each response as “pass” or “fail”. Which statistic is especially appropriate for their categorical agreement after allowance for chance agreement?

Correct answer: Cohen's kappa Cohen’s kappa measures agreement between two raters on categories after correcting for chance agreement.

• Pearson correlation Pearson correlation is for continuous variables and does not correct for chance agreement.
• Cronbach's alpha Cronbach’s alpha measures internal consistency of items.
• Spearman correlation Spearman correlation measures rank association, not categorical agreement.