Understanding Odds and Odds Ratios

Odds are a ratio of the chance of something happening divided by the chance of it not happening. They are useful for gamblers to determine fair bets. Odds ratios are commonly used to measure the effects of treatments or risk factors on the probability of a patient experiencing a specific outcome. The odds ratio compares the odds of the outcome for one group to the odds of the outcome for another. An odds ratio of 1 indicates that the outcome is equally likely for both groups, while an odds ratio below 1 suggests a lower likelihood of the outcome in the treated group.