In statistics, the odds ratio (OR) is one of three main ways to quantify how strongly the presence The sample odds ratio n11n00 / n10n01 is easy to calculate, and for moderate and large samples performs well as an estimator of the population. How to Calculate Odds. The mathematical concept of odds is related to, yet distinct from the concept of probability. In simplest terms, odds are a way of. Free online Odds Ratio (OR) statistical calculator calculates Odds Ratio with 95% Confidence Interval from a 2x2 table.