Odds ratio

The odds ratio is the ratio of the odds of the outcome in the two groups.

Odds ratio = (a/c) / (b/d)

Literature

• Sheskin DJ (2004) Handbook of parametric and nonparametric statistical procedures. 3rd ed. Boca Raton: Chapman & Hall /CRC.
• Bland JM, Altman DG. The odds ratio. BMJ 2000;320:1468.
• Altman DG, Deeks JJ, Sackett DL. Odds ratios should be avoided when events are common [letter]. BMJ 1998;317:1318.