Table 1

Average subjective probability of two primary diagnoses based on pretest with nine emergency physicians in the state of Washington

Diagnosis A	Diagnosis B	Probability (A)	Probability (B)	Probability other
Pneumonia	Pulmonary embolism	0.44	0.30	0.26
Acute MI	Type A aortic dissection	0.53	0.33	0.14
Tubo-ovarian abscess	Appendicitis	0.46	0.39	0.15
Subarachnoid haemorrhage	Meningitis	0.36	0.57	0.07
Kidney stone	Type B aortic dissection	0.49	0.38	0.13
Pyelonephritis	Abdominal aortic aneurism	0.52	0.34	0.14
Pancreatitis	Cholecystitis	0.42	0.58	0.00
Cellulitis	Deep vein thrombosis	0.56	0.43	0.01