Free Odds Ratio Calculator
Calculate the odds ratio from a 2x2 contingency table to compare the odds of an outcome between two groups.
Odds Ratio (OR)
2.4286
ln(OR)0.8873
Odds Group 10.4286
Odds Group 20.1765
Odds Ratio (OR) vs Group 1 - Event (a)
How to Calculate the Odds Ratio
Formula
OR = (a * d) / (b * c)
where a, b, c, d are cells of the 2x2 table:
OR = 1 means no association. OR > 1 means the exposure increases the odds of the outcome. OR < 1 means the exposure is protective.
Example Calculation
Group 1: 30 events, 70 non-events. Group 2: 15 events, 85 non-events.
- 01Odds Group 1 = 30/70 = 0.4286
- 02Odds Group 2 = 15/85 = 0.1765
- 03OR = (30*85) / (70*15) = 2550 / 1050 = 2.4286
- 04ln(OR) = ln(2.4286) = 0.887
- 05The odds of the event are 2.43 times higher in Group 1
Frequently Asked Questions
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