Calculateur de Rapport de Cotes — Formule

How to Calculate the Odds Ratio

Formula

OR = (a * d) / (b * c)

where a, b, c, d are cells of the 2x2 table:

  • a = exposed cases, b = exposed non-cases
  • c = unexposed cases, d = unexposed non-cases

    • OR = 1 means no association. OR > 1 means the exposure increases the odds of the outcome. OR < 1 means the exposure is protective.

    Exemple Résolu

    Group 1: 30 events, 70 non-events. Group 2: 15 events, 85 non-events.

    1. Odds Group 1 = 30/70 = 0.4286
    2. Odds Group 2 = 15/85 = 0.1765
    3. OR = (30*85) / (70*15) = 2550 / 1050 = 2.4286
    4. ln(OR) = ln(2.4286) = 0.887
    5. The odds of the event are 2.43 times higher in Group 1