Table 1. Classification table comparing test outcome with true agranulocytosis status.

Test result	Agranulocytosis		Total
	Yes	No
Positive: High risk	a=sk	b=x-sk	a+b=x
Negative: Low risk	c=(1-s) k	d=1-x-(1-s) k	c+d=1-x
Total	a+c=k	b+d=1-k	1

Cell probabilities are expressed in terms of sensitivity (s) and size of the HR group (x).