ratio odds odds correspond to a ratio in which the numerator represents the probability that an event will occur and the denominator represents the probability that an event will not occur. 'Odds' and 'Odds ratio' are different terms. 'Odds' is a ratio of probabilities. 'Odds ratio' is a ratio of two different odds. Odds are calculated as p / (1-p) where p is the probability of event occurrence. When p = 0, the odds = 0. When p = 1, the odds may be expressed as not calculable or as "odds against = 0". Odds may be expressed as p:(1-p). Odds may be expressed as p:q where q = 1-p. Odds may be expressed as a:b where a and b are multiples of p and (1-p). Examples of different expressions of the same odds include 3:2, 3/2, 0.6:0.4, 0.6/0.4, and 1.5. Odds may be expressed as "odds for" or "odds in favor" (e.g. 1:5 for a "3" on a 6-sided die) or "odds against" (e.g. 5:1 against a "3" on a 6-sided die). The term "betting odds" used in gambling that involves financial amounts in the formulation is not an "Odds" in the definition of the Scientific Evidence Code System. Brian S. Alper, Harold Lehmann, Joanne Dehnbostel, Khalid Shahin, Kenneth Wilkins, Muhammad Afzal Expert Working Group Agreement: 2022-03-22 vote 5-0 by Muhammad Afzal, Jesus Lopez-Alcalde, Philippe Rocca-Serra, Mario Tristan, Robin Ann Yurk ready for release