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.

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

Present            a            b
(Exposed)

Absent             c            d
(Unexposed)

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 <http://www.molvis.org/molvis/v5/p26/>
©1999 Molecular Vision <http://www.molvis.org/molvis/>
ISSN 1090-0535