From: Increases in the completeness of disease records in dairy databases following changes in the criteria determining whether a record counts as correct
FD +
FD -
Total
ND +
a (FD+/ND+)
b (FD-/ND+)
a + b
ND -
c (FD+/ND-)
d* (FD-/ND-)
c + d
a + c
b + d