Figure 1 of Hawkins, Mol Vis 1999; 5:26.

Figure 1. Calculation of Odds Ratio

Illustration of method of calculating a crude odds ratios from cross-sectional or case-control studies. Although odds ratios often are calculated from prospective study data, in general they should not be considered to provide estimates of risk.

 Attribute        Yes           No
or Exposure     (Cases)     (Controls)
-----------     -------     ----------

Present            a            b

Absent             c            d

Odds of attribute or exposure in cases:

(2 K)

Odds of attribute or exposure in controls:

(2 K)

Odds ratio:

(3 K)

Hawkins, Mol Vis 1999; 5:26 <>
©1999 Molecular Vision <>
ISSN 1090-0535