Test Sensitivity & Specificity
Disease
Disease
Present
Absent
Total
Present
Absent
Total
Test
Pos
Test
Pos
a: (True + ve)
b: (False + ve)
a + b
Neg
Neg
c: (False - ve)
d: (False - ve)
c + d
Total
Total
a + c
b + d
n
Test sensitivity:
The ability of the TEST to correctly identify those with the disease (true +ve rate): (a/(a+c).
Test specificity:
The ability of the TEST to correctly identify those without the disease (true -ve rate): (d/(b+d).