Table 4 Odds Ratio: For a given pair (x,y), the reporting odds ratio provides the “unexpectedness of y, given x” via the simple calculation (ad) ÷ (bc) as defined in the contingency table below. For example, the cell marked as a denotes the number of patients that took drug x (e.g., Vioxx), and experienced condition y (e.g., myocardial infarction). The other cells help to establish the likelihood.