The Odds Ratio (OR) is a statistical measure used to compare the odds of an event occurring in two different groups. It is commonly used in epidemiology and clinical research to assess the strength of association between an exposure (like a treatment or risk factor) and an outcome (such as a disease). An OR greater than 1 indicates higher odds of the event in the exposed group, while an OR less than 1 suggests lower odds. To calculate the Odds Ratio, you take the odds of the event in the exposed group and divide it by the odds of the event in the unexposed group. For example, if Group A has a 70% chance of developing a condition and Group B has a 30% chance, the OR would be calculated as (0.7 / 0.3), resulting in an OR of approximately 2.33. This means that Group A has more than twice the odds of developing the condition compared to {