Fig. 4: Two clinicians who have been trained to assess Murphy's sign in patients with abdominal pain do an actual assessment on 100 patients. A: A 2 х 2 table reflecting actual agreement between the 2 clinicians. B: A 2 х 2 table illustrating the correct approach to determining the kappa score. The numbers in parentheses correspond to the results that would be expected were each clinician randomly guessing that half of the patients had a positive result (as in Fig. 2).