Odds Ratio (OR)

The Odds Ratio gives the radio with which "cases" are exposed relatively to controls.

• With an OR of 1 the part of exposed persons in both groups has been equal.
• With OR less than 1 the part of exposed persons under the cases was less, with OR higher than 1 more than under the controls.

By means of a significance test one can check how statistically important this difference is. For rare diseases the OR can be set equal to the RR.

Alternative

• Risk Ratio/Relative Risk (RR)