Odds ratio is the ratio of odds between two groups. For example, let’s assume that you are trying to ascertain the effectiveness of a medicine. You administered this medicine to the ‘intervention’ group and a placebo to the ‘control’ group.
Odds Ratio (OR) = Odds of the Intervention Group / Odds of the Control Group
Interpretation
- If odds ratio = 1, then there is no difference between the intervention group and the control group.
- If the odds ratio is greater than 1, then the control group is better than the intervention group.
- If the odds ratio is less than 1, then the intervention group is better than the control group.