Table 2. A Unit Fragility Index of One.

a = observed number of subjects exposed with the disease. b = observed number of subjects exposed without the disease. c = observed number of subjects not exposed but with the disease. d = observed number of subjects not exposed without the disease. If the statistical significance of the outcomes is changed after incrementing by one, then the unit fragility index equals one.

Condition	With Disease	Without Disease	Total
Toxin Exposure	a - 1	b + 1	a + b
No Exposure	c + 1	d - 1	c + d
Total	a + c	b + d	a + b + c + d