Odds Ratio vs Relative Risk
| Disease Present (Cases) | Disease Absent (Controls) | Row Total | |
|---|---|---|---|
| Exposed | a | b | a + b |
| Not Exposed | c | d | c + d |
| Column Total | a + c | b + d | Grand Total |
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Relative Risk (RR) compares PROBABILITY.
(a/a+c)is the probability of exposure in one group.- It's a ratio of two probabilities.
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Odds Ratio (OR) compares ODDS.
- Odds = (Number of times an event happens) / (Number of times it doesn't).
(a/c)are the odds of exposure in the disease group (cases).(b/d)are the odds of exposure in the control group.- The OR is the ratio of these two odds.